Heat Treating thoughts, based on Scientific Evidence

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corerf posted this 21 September 2014

This may bounce around a bit, keep focused..... I will try as well....

So I mentioned a while back I'm taking metallurgy to assist with my hobbies. I have an oral presentation to make with four other students and our topic will be Lead/Antimony alloys and its similarities/differences to another well known binary solution, steel. In my research I have found a bit more than trial/error evidence that those of us who employ heat treating are not absolutely getting all we can from our operations and from possibly leaner solutions. So in short, there is some significant documentation (that I can to some extend understand now) suggesting or directly stating the conditions of dendritic lead/antimony solutions required to produce specific dendritic or micro crystal formation. Like steel, temp, soak and rate of cooling all play into the process. Restructuring the grain conditions, just like steel, adds or subtracts specific performance aspects to the metal. I will expound on my conclusions slowly over the next month or two.... but bottom line is I believe there is a condition and process that can be employed to both boost the strength of a given lead/antimony alloy and at significantly lower antimony percentages than I think ANYONE had thought. I also believe that similar to aluminum, second pass heat treatment may compound the grain refinement (adding more compressive strength) on any heat treatable alloy. Lastly I believe there is serious clout regarding sulphurs use as a possible grain refiner. There are more than a couple significant govt lab studies on grain growth, antimony precipitation and the conditions that create it, on the web and elsewhere. Remember its the carbon and its manipulation thats makes IRON/CARBON actually STEEL. Additionally its the antimony and ONLY the antimony that IMPROVES the strength of a bullet alloy. How the carbon and how the ANTIMONY are manipulated is what gives us out desired performance in there two solutions.

ANYBODY every water quench a bullet with Lead/Antimony (and the pinch of arsenic we all believe makes the magic happen) and the OVEN HEAT TREAT the bullet with the same accuracy as a NASA class heat treat company would a piece of steel flying into space? Not the kenmore treatment or the Maytag project at roughly 490 degrees (we think) but  within a COUPLE of degrees of the alloy critical temp?? I have NOT. There might just be a few BHN to be had during a second HT process further refining grain and locating more free antimony where it held us, on the outside of the bullet. Think about that!!~ One more reason for my heat treat oven to be PID controlled. The whole rise/ramp/soak which typically CANT be controlled in the Whirlpool or your Pro grade Wolf stove, can be controlled in a lab furnace or oven.

Remember more antimony on skin, less in core. Alloy composition will not change, just the physical location of the elements. Harder skin, softer core........

Im just saying'-------------     is this making anyones eyeballs rattle yet? Like brie cheese. Crusty outside, gooey inside. Able to obturate at lower pressure but be undamaged on its skin and not shed like a sheepdog. That sounds like a typical gilding metal jacketed bullet that was drawn and swaged- say the modern varmint bullet.

Bottom line is if I can (or anyone else for that matter) figure out a heat treat method that will yield BHN 30 with antimony concentrations below 3%, WOW!! Its all about how during specific cooling conditions, the antimony settles out AROUND the lead crystals and dendrites to form a barrier. The antimony can and does fall out of the eutectic composition (eutectic-think salt and pepper mixed perfectly with absolute perfect separation and locations of each salt and pepper granule- equilibrium) and congregate all along the lead crystal boundaries.  That can be controlled!!! Where the antimony GOES and at what concentrations it arrives there, can be CONTROLLED (to some extent, hence why we can heat treat today with success). The latter question will be---- can a caster employ the process by which the antimony behaves as desired.

The broad strokes--- 

We have all heated a pot or WW VERY, VERY hot. We then concerned ourselves with loss of precious metals at the top due to oxidation and separation. Then we flux and hope that we can retrieve the separated components. YES?? We do this as at high heat, sometimes molds fill out better with a a given batch. We try to cast as low as possible but poor fill out precludes a lower temp at times. Well I will not suggest but will state as fact, heat it up REAL HIGH and let it STAY THERE. Worry not about the loss, which may be less than .1% of antimony. At rates lower than 3% concentration, when the binary alloy is held at high temps (like the upper critical steel temps near liquid state), the antimony gets ready to GO PLACES. The antimony is out strength booster! Put it where it needs to go. Get it there through high heat. It has been suggested that the HT process on a bullet is merely like a case hardening. Its just a tough skin with soft core. This is true but not for the same reason as steel. Antimony freezes first from liquid and a mold cools from the outside in. This means that  a HYPER eutectic grain structure is formed on the outside of the bullet. Ever noticed that a HT bullet turns a darker grey following HT over time from oxidation, the NON HT version of the ams bullet color is still typical of nearly pure lead or pure tin?????? HMMMM thats because the antimony has precipitated OUT of solution, at extremely LOW total percentages forming a case hardened bullet. Think of the antimony as carbon in the parallel, steel. Case hardening adds carbon at higher percentages to the skin of a piece of steel. Antimony moves more freely than carbon as related to a bullet material. That antimony can be guided out of the core of the bullet to the skin, in high concentrations to where you want it to go.

When a frosty bullet comes out of the mold...... its frosty because (my new belief and understanding)  the antimony in solution, fell out of solution like rock candy out of boiling water and its cooling/freezing behavior is CRAZY and UNGUIDED in forming dendrites that go every which way. Its UGLY. Not pretty like smooth forming lead crystals typically are. No harm in that. but its not in a high strength configuration. Think a wood pile just dumped, not stacked properly!

These is some relation (I have yet to trip over the answer) to the super cooled state of the bullet melt. That is the place where the temp has fallen below the melt point of the alloy, but just won't freeze to a solid. If we are able to hold the alloy at the super cooled state and keep the dendrites (little snowflakes of alloy forming) from firing off, for a period of time, then the antimony behaves radically different and I believe positively for bullet making. During the super cooled state, the antimony REALLY takes action. Figure out how to HEAT THE LIVING HELL out of the alloy, then take it quickly to super cooled and keep it there..... then quench it REALLY FAST-- like ice water fast, maybe even salt water fast!! This is what I believe will be the magic process. During that paste stage I will call it, antimony is getting its job done. BEGIN SIDEBAR: What if the mold was a master mold, having 20-50 cavities. The alloy is poured into the master cavity with sprue puddles at top of each for continuous pressure on the mold. (so that the mold doesn't run out near full).Put mold in oven, heat to upper critical or past to liquid. So you can pour the molds and let them cool at room temp, then stick in oven. Reheat to FLUIDIZE the alloy and erase all bad juju! Then HOLD temp for needed period of time at VERY HIGH heat. Basically we need meehanite molds so that we don't warp at hold temps of 750 degrees. Then take the entire oven down to SuperCooled temp. Hold for a LONG SOAK. This is where the bullet takes on its magic skin. Then quench those bullets. I believe this simple (to type that is) process would generate the conditions needed to put antimony where it needs to be, relocating it from core. The mold might even need quenching with latter bullet removal and sprue removal. NO oxidation. No LOSS of alloy materials. Seemingly VERY expensive. Potentially harmful to molds or totally destructive. Im not saying it can be done----- thats asking a TON. Im just presenting a process which might result in the nearly perfect cast bullet if the appropriate arrangement is made. END SIDEBAR:

Unfortunately lead just behaves the same at all temps. Its just does its thing. Makes neat little face centered cubic crystals. I am not able to make ANY statements as to the TIN's action or reaction to ANY process. As far as I am concerned, its likely just a grain refiner altering the dendritic and basic crystal formation such that it happens in a manner beneficial to mold fill out. Period. It helps not in strength. The solder end of the world uses HYPO/HYPER eutectic mixes for specific soldering performance. I use HYPER Eutectic for field work so that the paste stage is very short, almost non-existent. The tin lowers the melt temp, helps it lay down and in right proportions, helps the solder freeze at a given rate desired. And yes it adds some corrosion resistance. Pure lead solder would not last long from corrosion. So I believe the tin does a similar job in bullet casting. FLOW, LAYDOWN, CORROSION RESISTANCE, LOWER MELT TEMP. Thats it. Id like to see what lead and antimony do in a different environment like an inert one. Say argon? Would it behave more like 20-1 or 30-1 bpcr alloy in fluidity and mold fill out.

I understand that if you buy lyman #2, cast a bullet, it hits the target... blah blah blah. Go ahead and keep casting, Im going to. Don't read or think about it. But someone needed a heat treated bullet and figured out what antimony did when rapidly cooled and got a BETTER bullet for a GIVEN purpose. At least I have a thread to reflex on that may inspire me in the future as I do the OLD WAY..... but conceive a NEW WAY.

Well we all want jacketed bullet perf from a cast bullet, right?? So rather than rest on my laurels and say what is will always be, I am on a quest to find the process to make that 30 BHN bullet on 1% antimony or less!! Why?? Its cheaper. Antimony is skyrocketing. So is tin. Hell so is lead. 

There is room for advancement. There is room for substantial improvement. What if we could make the 30 BHN bullet really malleable in its core, really, really, really malleable!! We have a bullet getting hit by 40+ KSI and terminating into a flesh brick wall. I want the bore to NOT bother the bullet eny more than needed, yet I want a silver dollar to come flying out of the pig I shot or the elk for dinner. Thats a jacketed bullet. A 454 casull hard cast bullet is NOT that bullet. Its a steel rod with penetration but no expansion!! A j bullet is designed in every directive, to penetrate SPECIFIC depth, expand a CERTAIN way, retain a GIVEN among of weight and shed energy a SPECIFIC way. Cast bullet...... well I shot THRU the animal, I shredded the animals skin and it dies 5 days latter due to infection, or I blew a plug of meat the size a small Hawaiian island out of the animal and after I dressed it I had 3 ounces of meat for dinner. We typically get TOO MUCH of what we want and lack balance (straight WW is our most balanced metal!!) I propose making by process, a thin antimony jacketed bullet. Microscopic jacket, BHN 10 core!! All by the phase changes (which are clearly documented) of the binary lead/antimony solution.  Now it may not be practical and I am willing to accept that. I am also will to accept the fact that it may be so friggen expensive to perform that I never get further than documenting the process with a single bullet as the completed operation. But no pain, no gain. Someone much smarter than me will find a way to involve the process economically down the road. Thats what China does. We make it, the old fashioned way. They Walmart it with some process and do it cheaper, faster (I didn't day better).

This is not an ahh ha moment. Its simply revelation of the “mystery metal” we use to make a bullet for today, and some direction to send folks off thinking. That and its really cool to ponder!! So anyway, I have “STIRRED THE POT” again. I did it with black powder manufacture (there is a better way, just laziness has set in at Goex!!). Im doing it again with the bullet. There is a better way, might be impossible like flying to the moon for work every day.... but if not for a few folks pursuing flight period, we would just be watching birds....... not traveling like them. CYA

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TRKakaCatWhisperer posted this 21 September 2014

Ok, I'm going to finish changing the oil and mowing the lawn and THEN sit down to read.

LOOKING FORWARD TO THIS ONE!

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onondaga posted this 22 September 2014

http://www.castbulletassoc.org/view_user.php?id=1362>corerf

Yes, I understand what you are saying and your hypothesis will work. There is a big BUT. You walk around Tin. The physical property that Tin adds to bullets is ductility,

Sure Antimony can be used to control hardness in overall alloy or on the surface with heat treating. Ductility is more important in a hunting bullet alloy. Antimony added to Lead to bring BHN up to 15 as cast is a brittle bullet that fragments on game because it is brittle with low ductility.

Your suggestion of an Antimonious BHN 10 alloy with a heat treated surface of 30BHN presents a problem for hunting bullets. The exterior is hard and brittle and the interior is soft and will over expand and splatter on impact with game with reasonable hunting loads. This is because of the lack of the combination of hardness and ductility. The primary guilt is in the lack of Tin so there is low ductility.

You mention Lyman #2, it has both a BHN 15 hardness and very significant ductility, it doesn't splatter or fragment because of the TIN giving the ductility to resist that. Gas checks also extend the usable ballistic pressure range well beyond the range of plain base bullets  from #2 alloy.  The #2 Alloy can also be heat treated to the BHN30 and higher but the ductility is not lost due to the 5% Tin in the #2 alloy.

If you want to ignore Tin and make an Anyimonious bullet alloy do what you want it to do by manipulating thermodynamics heat treating.  lack of ductility will be very related to your lack of Tin.  I don't see or expect any improvement over Lyman #2 Alloy or heat treated Lyman #2 alloy.

If your search is for  better paper punching bullet, you have a workable idea. If you are searching for a better hunting bullet alloy than Lyman #2, I don't think that will happen.

Gary

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Ken Campbell Iowa posted this 22 September 2014

i am stuck at square one ... are antimonial heat treated bullets only hardened at the surface ? or are they thru-hardened ?

in iron alloys, high carbon ( tool ) steels have the carbon evenly mixed, and thru-harden just from the hot-quench process. low carbon steels can be surface hardened by coating them with a small carbon particles before high heat and quench, the carbon infiltrates a few thousandths into the surface. thus case hardening.

in my simplistic mind i wonder if there is something that one could soak a lead bullet in at some critical temperature and induce surface hardening. an antimonial slurry ?

oh yeah, just to further reveal my inate slackerness, how come you cant soak a hot lead bullet in charcoal and get surface hardening ?


i applaud your project and i hope that you will keep us informed of all results and new insights .

ken

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corerf posted this 23 September 2014

Ken,

Glen Fryxell seems to believe the bullet is “more” surface hardened than thru hardened. I think thats a valid statement, most of the antimony, not all, moves to the rapid cooling outer shell of the mold according to the reports. But that all depends on how things are cooled.

From what I can see from the documents and what the lab did for testing, most of your antimony ends up concentrated in the exterior shell of the bullet.

Carbon doesn't have the affinity to hang out with antimony that it does with iron.

Interesting: Antimony powder or fines like in a pack hardening crucible, surrounding a pure lead bullet. Up to an appropriate temp, infusion occurs. The issue is the bullet would melt as the antimony would need higher heat than the lead melt point to start to move.

I appreciate you putting some thought into it. I was hoping at least a couple people would spend two mins contemplating it.

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Ed Harris posted this 23 September 2014

Go back and find Dennis Marshall's articles in American Rifleman back in the 1980s. Dennis was a materials scientist with the battery division of Johnson Controls and has published numerous articles on the subject. There are also some in the metals literature if you search.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Maven posted this 23 September 2014

Dennis Marshall's articles can also be found in E.H. Harrison's “Cast Bullets” (NRA publication); Lyman's “Cast Bullet Handbook, 3rd. Ed.;” and RCBS' “Cast Bullet Manual, number 1."

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Ed Harris posted this 26 September 2014

When the antimony is quenched in solid solution the bullet will be uniformly hard all the way through. When tin content does not exceed antimony content, quenching forms an intermetallic compound Sb--Sn which improves strength and hardness compared to either alloy constituent used separately. But if tin content exceeds antimony hardness will be lost in aging through cellular precipitation. A good lab exercize in stdength if materials.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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corerf posted this 26 September 2014

ed can you cite some references? My oral presentation for class would benefit from the study your mentioning.

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onondaga posted this 26 September 2014

http://castbulletassoc.org/view_user.php?id=1362>corerf

Citing Ed Harris as your source from this forum would be doing your homework correctly. He is well published and respected in the field.

Gary

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TRKakaCatWhisperer posted this 27 September 2014

onondaga wrote: http://castbulletassoc.org/view_user.php?id=1362>corerf

Citing Ed Harris as your source from this forum would be doing your homework correctly. He is well published and respected in the field.

Gary
Here's your reference, corerf: Ed Harris said: “When the antimony is quenched in solid solution the bullet will be uniformly hard all the way through. When tin content does not exceed antimony content, quenching forms an intermetallic compound Sb--Sn which improves strength and hardness compared to either alloy constituent used separately. But if tin content exceeds antimony hardness will be lost in aging through cellular precipitation. A good lab exercize in stdength if materials."

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Ed Harris posted this 30 September 2014

Dennis Marshall's articles cover it well, including metallographies and interpretation of the phase diagrams for ternary alloys.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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corerf posted this 30 September 2014

Thanks Ed for not misunderstanding the request for citation and data sources.

And no Gary I would not be doing my homework properly by citing “Ed Harris Said". I respect Ed and his wisdom and knowledge (and have no doubts about the validity of the statements), but if its not in print and I heard it over a cup of coffee and has no data to back it up, Might as well be Mickey Mouse. Give me any info Ed has ever put in print and it damn near becomes LAW. But a thread response is not viable data! You folks need to get the “I'm offended that you don't believe me” chip off you shoulders. Good grief. Two responses picking up anthers offense..... and Ed didn't seem to mind the request.

Just because its true doesn't make it useable. I can pull truths out of my butt randomly, nobody has to accept the truths till they are proven and documented.

Ed understood that and responded with charts and pictures under microscopic analysis. Thats what is needed.

Thanks Ed, as always, for nailing it.

All the best.

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TRKakaCatWhisperer posted this 30 September 2014

corerf wrote: ... but if its not in print and I heard it over a cup of coffee and has no data to back it up, Might as well be Mickey Mouse. ...  

yup, good research cites primary documents

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JeffinNZ posted this 02 October 2014

So a larger calibre bullet will be softer in the mild than a small calibre due to the cooling time?

I am sure a few years back I HT some .303 Brit bullets, took a BHN reading on the outside then carefully filed a cross section and re measured. The inner BHN was the same as the outer.

Cheers from New Zealand

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corerf posted this 31 October 2014

To JeffinNZ, yes bullets are through hardened.

To everyone:

So I am following up on my class oral presentation and my starter post regarding cast bullet heat treatment. So my initial thoughts of somehow directing Antimony to where and how I want it in the Lead-Antimony solution .... well it was a thought, not a principle. And it was for all intents and purposes not possible. It is but you might as well float a lead boat across the Atlantic as it would be easier to do. It would take a lot of work to produce the ONE bullet with perfect conditions during casting and well, its a great thing to have the Fed put some money into like exercising rabbits and giving them rubdowns after to see if they recover better. Its that difficult. But it could be done. I digress, as usual.

I have now dedicated MUCH effort, time, etc into the study of heat treatment of non-ferrous metals of many types. I have a pretty good grip on what LEAD and ANTIMONY do to and with each other in a bullet making material. Finally!

My class dissertation was on cost reducing techniques and performance improvements to cast bullets through heat treatment process. I DID NOT mimic Dennis Marshall!! Just ask the class.

In reality, very low Sb in the alloy has but one way to increase compressive strength, very well known and certainly covered by a multitude of folks in the last 30 plus years. But I have another item that has never been covered that I had a small epiphany over during tonights class presentation I made.

So “we” know as a fact that Arsenic is a grain refiner in the Pb-Sb alloy. Add a small amount arsenic, its like adding Vanadium to steel. It makes very small grain size and small is better than large in all metals (at least where strength is concerned). So it goes with lead too. Lead and antimony grain size matter. The arsenic DOES NOT make a bullet metal heat treatable.

This is a common misconception. The phase diagrams will clearly dictate this is true as will some actual testing of lead and antimony all by themselves in a heat treat environment. This has been documented in numerous govt papers, by Wiljen and by Dennis Marshall (and I am sure countless others). What Arsenic does is act as a grain refiner, significantly compounding the measured response during heat treatment. If you add arsenic to any lead antimony alloy, HT or not, it will act as a grain refiner. As per Wiljen, so will sulfur and a couple other elements. Heat treatment is NOT predicated by arsenic presence.

What I have seen zero documentation on is control of grain growth during the casting process.

Heres the crux: Big grains are bad and they form during slow cooling. Small grains are good and they form during fast cooling. Stupid convoluted grains (my word for really super strong grains) form during rapid cooling of arsenical alloys for sure! Arsenic creates minute nucleation points and those dendrites ram into each other and mess each other up real bad during rapid cooling. Thats bookoo strong alloy subsequently!

So what?

Since lead is at a very high temperature at room temp and of course REALLY hot at 200-300 degrees and its a fact that grains are STILL GROWING at 200-300 degrees, the longer a cast bullet is allowed to remain at the elevated temp, the larger grains will grow!! Regardless of your intent to heat treat or not. Matter of fact as far as I understand, that lead grain growth continues at room temp, forever! Just REALLY, REALLY SLOW!!

Of course the measurement of that is clearly defined by many folks: Water Quench your alloy and it goes say from AC BHN of 10-11 to a WQ BHN of 16-18. Not bad. For the water quench work you put in, you get some strength increase. But was that a form of heat treat or simply a method to TRUNCATE grain growth. I believe its grain growth! I have believed that quenching a bullet from the mold was a mild form of heat treatment. Its NOT, at least I don't believe it is. Its a grain growth inhibitor. So by adding arsenic to any alloy and adding a quench from the mold as rapid as possible (reducing it to room temp or below) will form VERY fine grain Pb-Sb microstructure.

So what??

So when you cast a bullet and let it air cool, its grain growth is LARGER, even in the presence of arsenic than it could be. If we quench the bullet, grain growth is halted quick(ER).

Then we heat treat the bullet. Bullet is in the lower transformation temperature zone and is a solid solution (not a slurry yet). Well the grains start growing at this temp!!! So we soak that bullet that we air cooled (maybe it was at 200 degrees or higher for upwards of 30 minutes on a hot summer casting day, may only 20 mins on a cold winter day). Thats 30 minutes of grain growth BEFORE you have heat treated (maybe you wait a month to heat treat!). Now you stick the bullet in the over at nearly 500 degrees, the zone where all hell breaks loose on the alloy and grain growth begins again. Regardless of the arsenic you added to refine grain in preparation for maximizing the strength improvement, your screwing up the material by allowing significant grain growth----- TWICE!!

This would (Ill say should since this is a theory which remains to be proven- but I will try) significantly reduce the overall strength improvements found during the precipitation hardening process due to EXCESSIVE grain growth.

Remember lead is hot at room temp, antimony is slowly traveling out of the solution and basically out of the bullet over time (at and below 6% antimony typical, not the real juicy high alloys). So since room temp is hot, 200-300 degrees is like having steel at bright red hot temps (over 1000 degrees). If this were steel, we are risking losing strength to grain growth for the same reasons. Translate that to 300 degree bullet material, same thing occurs.

So the thought: What if you water quench an alloy that you will ultimately heat treat (again low antimony below 6%)???

That first quench doesn't just make a bullet harder than air cooled for giggles, its setting the grain structure for optimal heat treatment. If the grain is GOING TO GROW during heat treat, you should try to ensure that the SMALLEST starting grain is obtained prior to the heat treat. Does that make ANY PRACTICAL SENSE??

So ideally, water quench from as hot a temp as the bullet will drop from the mold. Take it down with ice water potentially, so as to keep those few seconds of grain growth at 150-200 degrees in the core halted as early as poss.

Then IMMEDIATELY (like you do with Aluminum) send the bullet to heat treat oven. The longer the microstructure has to change due to the nature of the base metals, the less strength you will derive. Using the highest temp possible for the shortest period of time possible (alloy dependent!), soak that bullet and quench as usual.

Of course the aging process must kick in for a few days or weeks to build the final peak strength, as that precipitation process is very slow following the quench. But nonetheless.... it will happen. I think its a GOOD PLAN!! Or a BETTER PLAN

My second what if is this: Artificial acceleration of aging process like is done as a tempering for Aluminum. Yes I said aging and tempering in same sentence. Alum is hardened by aging at elevated but low temps (which is tempering since we are no where near any transformation temps). In a parallel to the Pb-Sb alloys, precipitation hardening occurs. 250-350 degrees for aluminum.......

but is there a temp above room temp that would move the aging process along in a single day or a matter of hours for a bullet material??

Thats the second experiment. I am a very patient person and could care less about how long a bullet after treatment takes to go from 13 BHN to 23. If its 2 weeks, that time is typically 2 years faster than Ill ever shoot the bullet given my crappy California lifestyle of paying everyone else's bills vicariously thru my taxes. But its a good what if!! If you can age aluminum and other non-ferrous alloys very accurately, lead alloys should/will be no different.

Is there a benefit? NO, NO, NO. Just go find something to do like load your favorite cartridge for a week or two. When your done, so will the bullets. But from a science perspective, it should and does matter that there is a possible accelerant process for aging.

None of this matters if all you want to do is shoot really rich antimony alloys. they need no processing. Linotype! Hard as nails right from the start and really over time, its not getting any softer (although since ALL phases of Lead/Antimony solutions are present in ALL ALLOYS, there will be some bit of precipitation hardened alloy that will shift over time and weaken the microstructure). it won't be but maybe 2 BHN points, hardly worth discussing. Just keep shooting the GODO STUFF then. But if I have stated anything true, then WE CAN MOVE INTO using VERY, VERY low antimony alloys and generate HIGH ALLOY compressive strengths with them. LOW Sb alloy is FAR cheaper than HIGH. And mastering the HT process SHOULD offer great flexibility in the FINAL WORKING BHN for a given alloy. Meaning if you use ONE ALLOY, you can shift its strength values anywhere from 10 BHN to 25 BHN WILLY NILLY if you have control of the HT process, the cast quench process and potentially SOME TEMPERING after HT to actually AGE the bullet to either a HIGHER BHN quicker or to REDUCE the BHN to lower than the HT process alone yielded.

If the J bullet folks make thin skinned jackets, thick skinned jackets, hard core, soft cores, banana peel starter cuts, hollow points, soft points..... all to alter the terminal ballistics and to some extent maybe interior ballistics....

WAY CANT WE MASTER taking a cast bullet and bending it to the EXACT form we want. Meaning we accurately define the bullets terminal performance and also its interior ballistic performance?? Why can't we define the perfect bullet like Sierra has, or Berger? I could care less about the void it has in it, the frosty finish, the lumpy base, etc. Thats all crap. Fix your mold or your technique and that usually gets taken care of. I am asking why we can't have a super hard bullet with massive tolerance of high pressure that when it hits bone acts like a wheel weight, with LESS ANTIMONY than WW alloy has in it?? Have the best of both worlds and all points in between. Cal it the Utopia alloy. Thats basically what the ASM does with other metals. They take an alloy and use heat and quench to shift its properties to EXACTING specs. I think we can do that with a bullet.

I didn't say it was worthwhile. This is “discussion". Thought provoking. It probably means nothing to everyone but me. Like moldy bread did to a doctor way back when. Its just moldy bread, it has no medical benefits.

So far I have found the RICH alloys have very few uses except fixing bullet fit problems, leading problem (but they start as many leading probe and they fix). I have found that the Heat Treated alloys lead less, have sufficient ductility to deform when you want them to and NOT when you don't need it, and will withstand the working pressures you define. So a part can be hard, but not tough. The high alloy bullets are HARD and strong, but not TOUGH! For game, we would like a HARD, STRONG bullet that is TOUGH. It will mushroom because its tough and not fragment. Thats really where heat treat makes sense. Its about getting the strength UP to xx KSI but still have ductility and TOUGHNESS. You can't do that with 15% antimony. It WILL fracture. Linotype for example. We actually benefit MORE from a heat treated, fine grain microstructure bullet at a modest BHN than we do a straight alloy bullet at same BHN. Antimony is out best friend, but its use is also the absolute enemy. It destroys your pocket book when you use much of it. I think a little dab will do just as well. A VERY SMALL DAB!!

Lastly I spent some time contemplating BHN vs compressive strength charts that Lee and others have put out. I realized that there is a correlation to MY personal experience and something I read. This is only profound to me. Im sure that ALL of you have concluded this and forgotten about it 40 years ago when I was eating light bulbs out of my childhood toys when mom wasn't looking.

So if a bullet is at 20 BHN, say it will supposedly YIELD (deform) at 30ksi and will stay elastic at or below 27ksi. If your bullet fit is poorer than it could be, or other factors such as propellant burn rate, etc produce LONG pressure curves with relatively low transients, by using a weaker bullet you may actually net better performance.

For instance: that 20 BHN bullet is in a cartridge that has a large throat, larger than you would like for perfection. Say you use a slow propellant like a rifle powder in 4895 class for sake of velocity and terminal performance. Its pretty long in pressure curve with not much POP at the first bit or burn (the opposite of Bullseye which is all POP and just about ZERO duration). That bullet won't have an opportunity to obturate (hit the plastic region ) for long enough or at all. It started its motion not fitting and will end its motion in barrel, still not fitting.

But take a bullet down at 15 BHN (clearly understated and rated for our 27++ksi service), use with the same propellant and same curves. Now the bullet may be low on strength by 3-4 ski, but it got an initial POP in the butt obturating the base (boy thats a can of worms I shouldn't have opened!!) potentially causing a better fit. Now maybe I used a bad example with a 3-4ksi differential, but if charts are accurate (and they are) then using a bullet slightly weaker than the working pressures dictate may very well be the absolute optimal condition.

Ive never considered this before. If the chart says 34ksi loads need X BHN, then I made a bullet AT LEAST X BHN if not a bit more. Accuracy though, as I think back, was just as good if not better, with slightly softer materials than the official X BHN material! I think this is some evidence of truth in the above statements. Too bad lead alloys cant work harden!

So anyway there is my sole contribution to the cast bullet society at large. No articles. It may all be BS. Sound neat though. Wont help you shoot better, probably bored you to near death 'cause you crossed that bridge same time as Moses crossed the Red Sea. But thats what the CBA wants and needs, articles, right? Not recipes for tuna salad, but an article having to do with a cast bullet.

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Maven posted this 31 October 2014

Send a PDF of your research to Glenn Latham ASAP, as it's exactly what TFS needs  (sorry about all the abbreviations)!:dude: 

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Ken Campbell Iowa posted this 31 October 2014

wonder what happens if we quench a bullet still in it's molten state when it hits the coolant ?

ken

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corerf posted this 31 October 2014

All right Ken, if your asking a serious question the answer is in the isothermal transform diagrams, if they exist, for lead antimony alloys.  You could try to use a littleton shotmaker as thats what it does. Make a big shot, like a buck shot. Don't think that will work.Otherwise drop some melt in a puddle of water and see what happens. Good luck analyzing the material as its arbitrary.

For all I know it might net the strongest low antimony alloy ever created. Like the prof says, “great question and thanks for asking". That might also be followed by, “I don't know!"/ Thats where Ill leave that.   I have another tidbit about the use of BHN to predict performance as well. BHN is worthless when multiple alloys are used in designing an alloy and really actually worthless for just about all bullet making processes. Almost all.

Room temp tensile. Thats what tells the story about an alloy. BHN is not worthy. It does NOT indicate accurately, strength and PLEASE strike my reference to it in the above thread. I have habits of referring to “what I thought” something was and mixing it with :"what it really is". See I rad Mr. Lee's book regarding bullet material, BHN and pressure. Maybe he wrote about Lyman #2 exclusively, buts its patent BS. Not his information, just the application of BHN correlating directly to alloy strength and operating pressures. I cry BS.

Bhn does not predict modulus. And modulus predicts or dictates strength. 

That should irritate some folks. I can make a bullet in the 10-12 bhn range thats STRONGER than a 25 bhn bullet. I can make a 30 bhn bullet based on heat treat and alloy selection thats almost less brittle than linotype. Well its guaranteed to be less brittle now that I think about it. Ill lean out the alloy to minimal, control grain growth and heat treat. It will make 30 BHN but slip like an 18 BHN. Using those unworthy BHN numbers as common reference.

As I drive in Los Angeles for work, I am stuck in traffic for hours. I have lots of time to design tube amps in my head, think about all the mistakes Ive made in life and also obscura. Some of the amps sound like crap. Some of the amps should be in the Smithsonian as exhibits in the American history section (at least I think so)! It all depends on what coffee I drank that morn, how many attorneys are pissing me off for work or how late I am to my first client. As I have been immersed in nonferrous metallurgy....... my mind is running with conventions I have thought I understood but those are being destroyed on an hourly basis by truth. I get some revelation in class, some more in reading, more in testing, then pow.... I get something that makes sense (again it may all be BS... you be the judge), but that comes a few days later when Im not paying attention. So as my day progresses, I draw conclusions for lots of things. This is one that has me ticked off. I swallowed a pill that said BHN is relevant. Its not.  Caveat: Its relevant to a SPECIFIC alloy for indicating heat treat progression without destructive testing!! Thats it. The rest of it is BS for bullets!

Bottom line.....if rockwell hardenss tests gave us a strength characteristic, we would not use room temp tensile, room temp charpy nor sub zero charpy to actually measure strength of material. Why is it we rely on Mr Lee's chart (God Bless Him) instead of actually measuring material? We all don't have the ability to characterize said material, or do we??

You all think about that. We simply use a stupid single point reference to gauge strength. And of course actual field experience, but how much can you really get out of a smashed fired bullet!!!!! If we built airplanes on BHN or Rockwell C or B, or any other hardness test, we would all be dead having attempted flight. Planes would fail daily.

Just another thought provoker. Ill have another before bed as I am at the Rose Bowl performing pregame and have a good 2 hour drive home.

Example: BHN 10. Withstanding 25ksi. Thats not what the chart says. But thats what is happening in real life every tie I pull the trigger on my 357. Up to 40ksi on 10-12 bhn. That too. Done it, reasonable accuracy too, no leading, no check. May not be ideal, but it proves the chart makes no sense. It must be a fluke. No its not. How? Thats not what the charts say.

Ductility. Toughness. Intergranular and intragranular strength though alloy selection and temperature control. Not hardness. Heck a diamond would do great in the 454 casull if that were the case. Or a carbide hunk. Or steel for that matter. If hardness matters most in characterization of strength, well then take it to an extreme and then get improved results. Its just of little importance. I suspect that btw 10 and 20 BHN is the sole window of operation that can be afforded. Outside of it like pure lead will have some use (bpcr, target handgun), but aside from that there is no need in our common cartridges. Even super magnums. Its all about the whole picture and BHN is just the left corner of the page. We have to read the rest of the page. 

Ductility (unless your making specialized tooling) is paramount in all metals that we use for just about everything. In bullets too. So is toughness. These are the strength indicators that must be quantified in a bullet alloy, not BHN. Ultimately all the wisdom of the sage old timers (just use WW with 2% tin for good fill out) actually makes some SCIENTIFIC sense now. But additionally, the sage old timers have been wasting GOOD WW's by using straight, when they could have leaned out that alloy significantly with pure lead and achieved the same or better strength, at lower cost, with better down range performance and terminal performance. Make pure lead better. Not make scrap work better. Use the scrap to make PURE LEAD the ideal material. LEAN alloys, lower BHN numbers (which have little relevance), less leading, better bullet fit, CHEAPER SHOOTING, heat treatment techniques.

Thanks for the typo patience earlier.

Cya later. BYW: I said id have another tidbit. So that tensile test that is so desperately needed per my above gutspilling.... where does that come from. In a nut shell here it is. For the layman who is still gainfully employed or has other responsibilities other than shooting and reloading, eating and sleeping. Put said bullet alloy in 30 cal, 220 grain form, air cooled as cast, cast at a GIVEN recorded temp, in a BIG VICE. Put a V notch as best you can with a file or hacksaw, pick an arbitrary but repeatable depth. Start a notch of some kind. Hit protruding bullet length with sledge hammer nice and sharp and cause it to break at that notch. Remember how you did it all and make it reasonably repeatable. We are not working for the govt and don't need a Mil cert. Inspect the failure for deformation prior to total failure. What does it look like. Do so with pure lead. Then WW. Then Lino. Then MONO if you have avail. Now you have some vague index to refer to. Ill be you can take notes on how it FELT when you hit the bullet. Did it feel easy and clean/snappy or did it feel like it hesitated and squished a bit. Now if the notes and the physical fracture are correlated with the BHN that you measured prior to testing, you will find a relationship. If your retired and bored stiff with spending all your time having fun, then you can take some retirement money and build a full blown min chary test hammer with a gauge you calibrate. if your really good with hydraulics and strain gauges, then build the tensile test with extensometer. That will give us EVERYTHING we need to now to make a Betty Crocker recipe book for casting for folks who just don't care except how good the chocolate cake tastes. Yes we have recipes but those recipes don't tell us squat about how they perform. Your toughest alloys will be some of the leanest, if they are heat treated. The most brittle will be the richest and the air cooled alloys. The one that hesitated will shoot better in all conditions than the one that gave in cleanly. Thats a BOLD statement I just made. But it is the truth. The ideal bullet is the one with the lowest BHN, that has the highest toughness with the leanest alloy. As close to pure lead as we can go and not be pure lead. Unless you have a very specific application. 

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corerf posted this 02 November 2014

Just a reminder, this thread is not to build a stronger bullet, that been done. Its about optimization of a given alloy and the LEANEST alloy possible.

To Ken Campbell,

I have a direct answer to your question and I believe it has been confirmed as the UTMOST in performance improvement.

Per ” Microsegregation in the Lead-Antimony Alloys” research document from the Naval Research Lab, Wash D.C. (AC Simon and EL Jones)

They did perform a direct test on .01% Antimony lead alloy via multiple angles. Slow cooled and instant chilled were two of them.

The microstructure of the slow cooled showed really FAT dendritic growth and LARGE diameter filaments and branches. So BIG GRAINS!! And big grains are not a good thing unless you want purest, dead softest lead in its fully annealed state. Absolute softest material to be had.

The microstructure of the CHILLED alloy was diametrically opposed. It showed the tiniest of dendrites, and an exponential increase in their numbers. The branches of the dendrites were teeny tiny, evenly spaced but the entire structure is distorted and twisted buy the violent cooling. There is a current of cooling that flows thru the alloy and it makes a storm of sorts tossing the dendrites as they form around and convoluting them. So that we all know what convoluted grain structure is all about and its benefit in cast material: Cast material usually trends to have very orderly LARGE grain growth in whatever form it is going to take, due to SLOW COOLING. Symmetry sometimes too in the grain. It almost predictable. If you understand that dendritic crystal formation is BAD JUJU for strength because of its large predictable structure and ease of INTRA granular fracture (the grains actually are so big they break in two, rather than grains separating from each other), the converse, a wrought metal it the opposite. The wrought form of the metal has a convoluted broken or “refined” minute dendrite structure due to you beating the hell out of it. BIG dendrites are crushed (slip occurs) into little stuff, refining grain, adding dislocations to the crystal structure which is the premier way to add strength to a metal. More dislocations, more BALLS in the metal (well until it fails, then you put too much in). Lead can't be work hardened due to its bonding and other properties. It softens. So we can't beat the hell out of a bullet in a swage and make it better. We hurt it. That TORRENT of crystallization that occurs during the UBER RAPIDO quench from liquid alloy is absolutely a parallel to what taking a casting of work hardenable metal and adding work to it does. It makes it a wrought structure. You want FORGED PISTONS, FORGED CRANK, FORGED RODS, ARP FORGED ROD BOLTS in your hot rod (they have copies work added). You don't want CAST PISTONS, CRANK, RODS (ZERO WORK ADDED)..... they are not going to take your 6,500 Rear Wheel HP very well. This is why Kens question was a smack in the face. I assumed it would be better for all the correct reasons. But I have seen pictures of the microstructure now and MAN o MAN its the super Duper fact of the year.

Quoted from the above reference report.

Check this out!!

” In such a zone the atomic distances are short and the concentration gradient large so that a maximum solid solubility may be expected to occur during solidification"

Further more:

” The inability of the antimony to diffuse rapidly from solution into the large amounts of lead first formed will cause a sharp change in concentration of the liquid toward the eutectic composition, with subsequent separation of metallic antimony in a recognizable form".

So in the “Check This Out” Ill paraphrase:

The crystal structure becomes optimized to generate what I will term as near perfect, finest granularity lead-antimony microstructure retaining maximum antimony in solid solution. That is the 100% martensite (steel reference) of the lead alloy world. The strongest matrix that can be generated for a given alloy and the most thorough generation of that phase (alloy structure).

So in the “Further More", Ill paraphrase again:

Since the Eutectic phase of Lead-Antimony is the strongest form of the alloy (electrochemically), then more eutectic is better. Since Eutectic is 17.5% (that number is subject to the phase diagram referred to, I have seen the number flex on a few of them but thats the general rule), this means that rather than the antimony just hanging around willy nilly and diffusing or precipitating or otherwise landing in a phase which is NON-Optmal for strength improvement----- it forms the Eutectic phase component nearly 100%. All the antimony gets utilized in creation of the Eutectic Phase structure, rather than another less desirable phase. More Eutectic, stronger. Scatter the Antimony, less strength. 

To clarify for those that may misunderstand: If I take a teaspoon of sugar and pout it in a cup of flour (just dump the spoon), there will be zones of 100% sugar, to 0% sugar and possible all parts in-between. As example, there will be a zone of the cup of flour that has 17.5% sugar. Consider this Eutectic. If we took that same TSP of sugar, took precise amounts of flour and bonded them so that each bit of flour was at 17.5% sugar and did so with ALL the sugar avail, the flour would still be at maybe 10% TOTAL sugar but parts of the whole CUP are at 17.5%. If we color it black (the Eutectic) and HOMOGENIZE it into the flour (evenly distributed it), you would hav pepper like flakes of EUTECTIC in a white base. And you may think that isn't very much BLACK to spread around, but that flour wouldn't be like a sack full of weevils, no it would be like you turned the WHOLE MIX charcoal grey or maybe a lighter shade of grey. Thats POWER. That makes stuff STRONG. Tensile strength goes through the roof quickly. Even with as the labs studied, .01% Antimony, the Eutectic formation was visible under an OPTICAL MICROSCOPE and thats significant. If we raise the Sb content to say .5%, Holy Sheep Dip Batman.......... So hopefully that clarifies to some extent why the Eutectic formation in an alloy is so darned important and if we can harvest that or direct that to happen, we are better for it!

(Minor redirect): Ed Harris responded to the thread very early, noting Dennis Marshall and precipitation hardening being the primarily booster process found in LOW ALLOY materials- lead material that is. Yep, thats true. But my first thought was spectacular and basically impossible but it IS THE TARGET. Im right back where I started. ED, I want to PHYSICALLY force the Antimony where, when and how I want it to exist. The statement, Prec Hardening won't allow that, especially in LOW ALLOY material is correct. But its NOT CORRECT. Through KENS METHOD (yes its impossible or nearly impossible), you CAN HAVE THE CAKE I WANT TO EAT. Ill say thank you for sending me to Mr. Marshalls documents as w/o that direction I would not have dug deeper to find that my hypothesis is FACT. I can tell the Antimony how to act. Thats what Heat Treatment allows. But your thinking was narrowed by acceptance of practical limits. Expand beyond practical and we CAN put Eutectic together in LOW ALLOY materials and do it with HIGH SUCCESS and almost completely. (END Minor redirect)

Now if you add the CHECK THIS OUT grain refinement (which is just as bad ass as any metal guy could ever want) to the FURTHER MORE (which is as electrochemically stable a phase as can be had per unit of antimony available)............ BY GOLLY we have the ultimate bullet material!!

This document is just the cats meow. The govt really kicked butt on this one. Ill bet Dennis Marshall used this to form at least one if not several of his documents. Since casting a bullet as far as I know to date, is so difficult to do from liquid stage to instant chill, its not relevant. But its IS!! Because what ever we can do to create as CLOSE A PROCESS to instant chill as possible, the closer to bullet strength nirvana we get. And conversely the farther from this process we get, the poorer a bullet we create.

Now I think Ill finish with this. Im sure a bunch of folks have read this and said, gee this guy is JoeB w/o the WEED/PEYOTE as Ed Harris has indicated may be trigger for another soothsayer. But THIS IS IMPORTANT TO BOB the average caster who shoots his 1911 quite often with target loads.

The industry has focused on productivity, create a room temp alloy using air cooling (natural) and cast with it. What ever Antimony is required to generate a given needed strength factor, thats just a cost of doing business. But we are in a tech smart, lean production world. We take turds and make energy from them, fertilizer, probably extract all the Viagra that Phizer resells from it too, since it doesn't metabolize fully and its still viable even after it leaves your body. Why not reclaim it....

I digress..... Laugh a little would you. You'll feel better, especially if you know little blue was Johns little blue and Phils little blue right before you received your bottle!

Anyway, laugh agin, say Im crazy. But heres the important point. WE as a cast bullet shooting SOCIETY have beed set in out ways for some time with little goading to change. It works, why change. Well costs are on the rise. Thats whay LEAN MANUFACTURING is the name of the game. Thats why men have ben replaced with machines in factories. LEAN MANUFACTURING.

Granted we can't really replace ourselves in the process, not the lead, nor the time, not the electricity or gas to make the needed heat...... but we can refine our use of alloy to produce a THIN minimalist approach to bullet making, optimizing nearly pure lead but obtain higher alloy results.

If BOB the above mentioned average caster is low on Wheel Weights, then he is LOW on Antimony. But his scrap yard has sheet lead at a mere .75/lb. Wowzer thats cheap. but pure lead won't do well in his 1911 with his red dot loads, already tested to find that its too weak to support his barrel, or load, etc. BOB need NOT go find more WW, which my STATE OF CONFU-Fornia has outlawed. NAY..... just wet it down, ALOT!!!! Make that last bit of WW shine like it never could before by LEANING out the alloy. Natural gas is cheap here in CAL. My oven in very efficient. Better yet, a bucket of water at my feet when I am casting is really low cost, as long as other states don't refuse to sell my pitiful state drinking water. So if I ensure by simple process that I have included just a pinch of the needed grain refiner (sulfur or arsenic) in my melt, lean that alloy well below 1% in this case (which actually helps the FILL OUT PROCESS by boosting the surface tension reduction properties of tin for obvious ratio reasons), drop that really hot bullet in water and get the same bullet you get with wheel weights straight.

Am I nuts or am I making sense?? Again I could care less about you folks that have retirement money to spend at the Indian Casino every Wednesday, since Im paying for your healthcare. No problem. But for those of use who don't act like my mom and dad, going to the Indian Casino every Wednesday for the buffet (what a friggen rationalized farce, might as well be a heroin addict and say its cheaper than Oxycodone so its better for the countries financials and better for you!)...

where was I??? Oh yea, Indian Casino every Wednesday for the buffet, and you have to work to play or hunt or shoot or run your bullet making business or what have you......... then this matters a bunch. if in fact you can't or won't apply the information or technology as I could call it today, then in 10 years when you are OLD FARTISH and running short of retirement money because you SPENT too many days at said Indian Casino for too many years, then this will be of HUGE benefit to you.

Did you know the world supply of NICKEL is extremely LOW and not because we don't mine it any more?? If you think stainless is expensive now, give it another 10 years. Build a few more Disney buildings of 100,000 ton of Stainless... Equate that to ANTIMONY. Wowzer, we are kind of going the same direction. But lead, goes round and round and round and round. And bad ALLOYED lead does the same. If you can make a few very educated assumptions, you can likely produce a very VERSATILE alloy from scrap or pure lead, whichever is cheapest and most avail. Doing the best with the most prevalent element, lead. We do it with steel. We use as MUCH LOW CARBON plain carbon steel as we can, just IRON, CARBON and some silica or other thing there is more of than water on earth to refine grain. Simple, lean, most cost effective, VERSATILE---- Skyscrapers to Car Sheet metal to food cans to nuts and bolts. Wow how versatile. We should have a 2% and below alloy that through proper technique, we can attain highest level performance to almost pure dead soft conditions. I don't mean 1.5%, I mean .3% Antimony!!

Ken Campbell, I sure appreciate the question. Like the Prof says, ” great question and thanks for asking". This time I don't follow with “I don't know". And Im not being funny AT ALL. Thank you. It further reinforces the need for ALWAYS WATER QUENCHING your alloy, no matter what the need is, but do so with INCREASINGLY LEANER material to offset the effect of quenching. The process will indeed save significant money over the lifespan of the typical serious shooter. 

Quench for Dollars. Your wallet will thank you.

Sunday sermon concluded.

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Pentz posted this 02 November 2014

My quick read of this wall of text (NO insult implied) is that slow cooling results in large crystal growth. Same thing in cooking sugar-rich recipes.

As an archaeologist (now retired) I was grounded in earth science. Granite, for example, cools slowly at depth and has huge crystal structure. Obsidian cools instantly; the flakes are still used in surgery where ultra-sharpness is required; it fractures on the molecular level. No surprise that alloy crystals act accordingly.

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