Flash Hole Diameter’s Effect on Burn Efficiency

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Wm Cook posted this 25 November 2023

I’ve been working on a project to see the equivalency of SR primed .308 brass to LR primed .308 brass.  The initial effort compared LR Lapua with a .079 flash hole to SR Lapua PALMA brass with a .059 flash hole.

Initial results were as you would guess.  Faster rifle powder (2400, 4227) shot similar SD/ES while when using medium burn rate powder (RL7, 4895), the SR showed incomplete burn with wide SD/ES.  As a side note both the  SR & the LR burn rate (SD/ES) deteriorated with slower powder.   This was with a .308 Winchester, 205g bullet @ ~1700fps.

Comparing LR/.079 flash hole to SR/.059 flash hole is not comparing apples to apples.

As I’m about ready to embark on incrementally enlarging the flash hole size I thought I would throw out a shout to see if anyone has been down this path before.  Thanks, Bill Cook.

Patience isn’t a virtue, it’s a delay tactic.

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Larry Gibson posted this 25 November 2023

 This may give you a bit of insight.  I now use cases with the flash holes drilled out for my 308W cast bullet match loads In LC Match cases, 16.5 gr Alliant 2400, 30 XCB bullets].  The last 10 shot test I chronographed (Oehler M35P gave and ES of 18 fps and an SD of 5 fps.  

Drilled Flash Hole High Pressure Test; 308W

In the past I have posted this explanation of why I drill out flash holes for use with low end reduced loads.

 

I shoot many thousands of squib loads in various calibers but mostly in .30s. Many of these are rimless cartridges; 30-06, .308, .308 CBC, 7.65, 7.62x39 etc. The squib loads I shoot most often is a Lee 314-90-SWC-TL over 2.7 to 3.2 gr of Bullseye depending on the cartridge. Velocity is around 800 – 875 fps. I found a long time ago the shoulders do in fact get set back with light loads such as those. With many cast loads that use normal weight bullets in the 1600 to 2000 fps range there was little setback. It basically is a matter of the psi the load generates.  It takes roughly 7,000 psi (depends on thickness and hardness of the brass along with how much the case needs to reach the chamber walls.

 Measurements of shoulder set back or increase are easily taken with a Stoney Point tool. There have been basically the two theories regarding the cause; the firing pin blow theory and the primer theory. I ran the same tests with a fire formed case and inert primers; headspace was not changed. I then used the same fire formed case with live primers. In as little as two firings there was a measurable decrease in headspace. After five live primers the fired primer was noticeably backed out after firing. NOTE: this increase in headspace was with case taking LR primers. I never experience the problem with the .222  Rem or the 5.56 NATO.

 Using #d drills I gradually increased the flash hole diameter with a progressively larger drill. Using a different fire formed case with each larger drill and firing 5 primers I then measured the headspace before firing and after. As the size of the flash hole increased the headspace decrease lessoned. With a # 29 drill I no longer got any decrease in headspace.  I dedicated five .308 cases and five 30-06 cases that were well fire formed to their respective rifles chambers and drilled the flash holes with the #29 drill. Over the next few days I fired 50 shots with each case. There was an indoor 50” range where I was stationed so it wasn’t all that bad.  After the 50 firings there was negligible change in headspace with any of the five cases of each cartridge. The results of my test firmly demonstrated to me that it was the force of the primer explosion that drove the case forward and set back the shoulder. The squib load does not have the pressure to expand the case out to fit the chamber. By drilling out the flash hole the force of the explosion mostly went directly into the case as there is little rim left to contain it. Two other side benefits that were unforeseen; the extreme spread and standard deviations of the velocity readings improved and the case position sensitivity of the small charge was greatly reduced.

 As a result of the above tests I dedicated fire formed cases for squib loads for each rifle in rimless cases and drill out the flash holes. I have fired them many, many times now with no further change in headspace. Besides the squib load mentioned I also use 311631 (# may be wrong but it’s the 118 gr GC 32-20 bullet) with Unique in the above cartridges loaded to 1400 fps or so for a little more powerful small game load. The flash hole drilled cases work just fine for those. I now use the flash ole drilled cases for all my rimless cartridges with squib and really light loads.

Further  pressure testing in the .308W the last few years indicated that loads with a psi above 12,000 will obdurate sufficiently to prevent the primer from driving the case forward thus setting the shoulder back.”  

 Since then seems like every time the subject comes up we get admonitions not to do so because it is very “dangerous” should the cases with such drilled out flash holes be used for a “regular” load.  Having Previously tested such cases with “regular cast bullets loads creating 28 – 30,000 psi (measured via an Oehler M43 PBL) I have endeavored to ascertain the danger of loading such to the psi of “regular” loads at 55,000 +/- psi.

 I had enough cases LC 92 7.62 NATO (308W) cases I was going drill out the flash holes to run a series of 10 tests using five 9 shot tests and five 8 shot tests.  I would run a test with the flash holes as they were (.061&rdquo and then increase them in size incrementally to .140”.  That is the maximum size to enlarge the flash hole while still retaining enough of a shelf for the primer anvil legs to rest on. I used numbered (#) drills alternately from #44 up through #28 to enlarge the flash holes.

Here we see the cases with the flash holes drilled from “as issued” on the left to #28 drilled on the right;

 

The cases were FL sized in a RCBS X-die the loaded with pull down M80 bullets (147 gr FMJBT) over 43 gr of IMR 4895 with WLR primers.  The loads were tested on 2/25/2019 in my test rifle with a 24” barrel.  The Oehler M43 PBL was used to measure velocity, pressure, etc. I could see no difference in the appearance of the primers after firing.  Have a look for yourself;

Here is a compilation of all the data measured during the test.  I’ll be darned if I can see any meaningful difference between the first load with “regular” .061” flash holes and the last test with .140”.

 

Throughout the test the sky did not fall, Humpty did not fall off the wall, the chicken made it across the road and no collusion between Trump and the Russians was found………and I’m still alive and the rifle did not blow up……… It appears, based on actual test results, using cases with drilled out flash holes might not be as “dangerous” as some thought……… 

 

  Completed the 2nd test using 168 MKs over 41.5 gr IMR 4895 yesterday. Shot four 9 shot test groups using the cases with; flash holes as issued, then three other groups with flash holes drilled with #40 drill (.096"), #34 (.111") and #28 (.140"). The results;

With as issued flash holes: 2653 fps SD 16 fps/ES 53 fps; 56,000 psi SD 1,600/ES 4,800; group 1.69"

With #40 drill (.096") drill: 2646 fps SD 9 fps/ES 31 fps; 54,900 psi SD 1,300/ES 4,200; group 1.45"

With #34 drill (.111") drill: 2646 fps SD 19 fps/ES 61 fps; 54,700 psi SD 1,800/ES 6,000; group 1.37"

With #28 drill (.140) drill: 2641 fps SD 12 fps/ES 43 fps; 54,000 psi SD 1,100/ES 3,000; group .945"

The first 2 shots (foulers) were slightly out of the group and gave the 2 highest FPS and psi. That raised the averages above the others slightly. The test rifle normally shoots 10 shots into an average of 1.2 - 1.4".

All the data are once again within the normal test to test variation of the same load. Nothing indicates any "danger" from using cases with drilled flash holes, even with normal high pressure loads with jacketed bullets.

Again, the benefit of using such cases (those with LR primers) is with gallery type loads (cat's sneeze, mouse fart, squib, etc.) that do not generate sufficient psi to obturate the case. Using such cases in push feed actions, especially those with a plunger ejector, w/o drilling the flash holes can lead to shortened case headspace which then leads to failure to fire and/or failure to extract. Drilling the flash holes out alleviates that problem with these type loads.

 

"I never was concerned about increased pressure of the powder charge from larger flash holes. I do have a mild concern about increased pressure in the primer itself increasing the chance of a blanked or pierced primer."

That is one of the main concerns that is always expressed. If there was greater pressure in the primer with a drilled out flash hole than with a standard flash hole don't you think it would manifest itself in a greater flattening of the primer? Yet we don't see that at all in either test. The flatness of the fired primers regardless of flash hole size is identical. Thus far I have fired 136 cartridges at 56 t0 57,000 psi (measured) w/o a single indication of any greater primer flattening with drilled flash holes vs "standard" flash holes.

Perhaps there actually isn't any greater increase in pressure inside the primer? Or if there is an increase it is not a sufficient increase to pose any problem or danger. There was absolutely no indication there was in increase in pressure inside the primer cups.

A further argument, if not the main argument, against the use of drilled out flash hole cases for gallery loads is that if you inadvertently use them with a standard load it could be dangerous. Thus, if you have a standard load that doesn't pierce or blow the primer and inadvertently use a case with drilled flash holes it appears there really isn't any concern. I am not suggesting whatsoever that full power loads be developed and used with cases having drilled out flash holes……I do not do that. The point of this test was to determine if there is a danger from increased pressure if using a case with a drilled out flash hole.

What I am suggesting is the use of such cases with drilled out flash holes should be used with gallery or other low level cast bullet loads. The purpose of drilling out flash holes for use with gallery or other low level loads is to negate the headspace of the case from shortening with repeated firing from the primer pressure in push feed actions. That is all.

LMG

 

Concealment is not cover.........

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Wm Cook posted this 25 November 2023

Thanks Larry.  Should have known you've already been there.

Here is a compilation of all the data measured during the test.  I’ll be darned if I can see any meaningful difference between the first load with “regular” .061” flash holes and the last test with .140”.

  • For the LC cases you're using now what size did you drill the flash hole to?
  • And is it true that the only difference in magnum primers and standard primers is the hardness of the cup? 
  • Did you notice SD/ES deteriorate as the powders got slower?

As always, thanks for sharing your knowledge.  You really should write a book.  This is as far as I've gotten so far.  Bill C.

 

 

Patience isn’t a virtue, it’s a delay tactic.

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rhbrink posted this 25 November 2023

Years ago when I was shooting BPCR the rage was to reduce the primer flash hole and reform the primer pocket to use large pistol primers. I bought a set of dies to do just that and went to work on my 38-55 brass. I will say that you need a very strong press for this along with an anchored bench and strong arms and plenty of fortitude. And it turned out to be an absolute waste of time as near as I could tell. I wasn't much into chronograph work at the time as it's a lot of hit and miss with black powder, too much smoke and stuff flying through the chrony to get a bunch of good readings. 

Fast forward to the present time, I decided to get that rifle out of mothballs and shoot it during the Winter months as my favorite breech seating rifle is a pain to work with in the cold. Lube gets cold and stiff along with arthritic fingers, and just too much stuff to fool with to have fun. So, the first box of 38-55 brass that I picked up is the brass that has the reduced primer pockets and flash holes. I have more brass with normal primer flash holes along with large rifle primer pockets. After reading the above statements I will do some load development comparing large flash holes to reduced ones to see if I can detect any difference. Plus, this time around I will be using a scope as compared to the first time I was using iron sights. Eyesight ain't as good as it used to be either.

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Pentz posted this 25 November 2023

Conversely John Schauf up in Puyallup has forged the path to smaller flash holes for the 32-20 CPA using Starline brass.  He built a swage interior to the case with a exterior anvil to uniform the flash holes to .075/1/16".  He's set the 5 shot group record of 0.164 and dominates the matches at Paul Bunyan and Clark Rifles.   But I agree with enlarging for the military class and, possibly, others of which I do not use. 

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9.3X62AL posted this 25 November 2023

I haven't done extensive research on this subject matter regarding 'LR vs. SR" and flash hole variance questions.  I would need better hardware and a stronger skill set to arrive at any worthwhile conclusions, and others who clearly have what I lack in these regards have already cut this trail.  I trust and respect their findings posted above.  

I rate myself as a 'Fairly competent' caster and shooter, most of my hobby activities centered on hunting loads and practice ammo for hunting and personal defense.  I want as much accuracy as I can get for a reasonable investment in bench time and effort, but everyone's equation varies--depending upon the end goals.  Gotta please yourself in this life.

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Ken Campbell Iowa posted this 25 November 2023

great stuff guys ... some real shootin goin on here ...

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RicinYakima posted this 25 November 2023

"You gatta please yourself" a great line from Ricky Nelson's Garden Party song.

 

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Wm Cook posted this 26 November 2023

Here's the background data that I pulled out of looking at LR primers vs SR (.059 flash hole primers).  This thing started about a month ago when I was getting nervous about ever finding any LR primers.  Despite what people have said on the forum, they are still scarce.  Local dealers would get a few in but all limited the the quantity to 1000.  With the condition of the world today I'm still thinking that we're one unintended international incident away from not seeing any LR primers (bulk, 5000 at a time) for a long spell. Small piston and small rifle came back on the scene, but at a high price.  Midway was the first to sell 5000 quantities of LR primers about a few weeks ago and now they are sold out.  So thinking that LR primers were an endangered species I wanted to see if sr primers would work for .308 Winchester and 7.62x39.

I'm enamored with Lapua brass since been using it for the past 30 years. When the .308 Palma brass came back in stock I bought a couple hundred and ran the LR vs SR with the .059 flash hole.  Just a bit of background here: The Lapua Palma .308 Winchester brass is designed for long range competition with loads such as the Lapua 167g Scenar bullets, 45+g of N150 @ 2800 fps.  The small flash hole is intended to shoot the primer charge into the body of a case that is at or near compressed load. 

Asking it to improve anything with a case half full or less of faster power was a stretch. Thus I am working toward equalizing the performance of large rifle primers with small rifles.  What Larry described was a good moral boost.

With my 308W cast bullet match loads In LC Match cases, 16.5 gr Alliant 2400, 30 XCB bullets].  The last 10 shot test I chronographed (Oehler M35P) gave and ES of 18 fps and an SD of 5 fps. 

Attached is the data I pulled together.  The first chart was an apology to John who accepted my claim (with just a little skepticism) last October that the powder position was causing my consternation of shooting groups one minute and minutes later shooting patterns. Five would stick and then out of the blue I'd shoot a three and two or a two, two and one!!  I blamed it on powder position since I started to using a holding block about the time when things went south.  No offense intended for anyone living in the Southern part of the US.  But I was wrong.  I tested with the powder tilted to the nose, tilted to the base and with the Missouri roll and found virtually no difference in vel or sd. 

Pentz comment about John Schauf up in Puyallup was interesting.  Previously Bud posted that his cases (32/20?) were about 2/3's filled as I remember and that adds to the conversation of powder position and consistent burn rate with cast bullets. Thanks, Bill.

 

Patience isn’t a virtue, it’s a delay tactic.

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mashburn posted this 26 November 2023

To Larry,

This is a very informative and interesting post. You answered a lot of things that I have been wondering about. Keep up the good work.

Mashburn

David a. Cogburn

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MP1886 posted this 26 November 2023

As good as Larry's post and testing, it mainly over covers the 308 size case. Yes I know he mentioned some other 30 calibers, but I'll bet the testing on those was not nearly as extensive.  So one can't form a solid theory on this because there are hundreds upon hundreds cartridges. Nor does it conver pistol/revolver cartridges, shotshell, and muzzle loaders. 

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Larry Gibson posted this 27 November 2023

MP 1886, you're correct, I have not tested other cartridges as extensively.  However, once proven it is no longer "theory" but is fact.  I have, indeed, used numerous other cartridges of various calibers from using LR primers with the flash holes drilled out.  The end result has always been the same; excellent ignition with less powders position "sensitivity"'.  I've never, have had any indication of increased pressure when pressure testing many of those cartridges or just shooting them.  Perhaps you have results from such tests you've conducted that demonstrate something otherwise?  Or is it just conjecture on your part?

As to shotshells and muzzle loaders; The flash hole in a shotshell is self contained in the primer so there is no flash hole in the shell to drill out. As to muzzle loaders, they don't have cartridge cases let alone primer pockets with flash holes so, again, there's nothing to drill out.......... 

 Here's another test, though not as complete/extensive as the 308W test, I completed about 4 years ago which covers two pistol cartridges. The end results are the same; no increase in pressure with either high pressure or low pressure handgun cartridges.

Drilled Flash Hole Test; 44 Magnum and 45 Colt

Completed the test yesterday 29 April, 2019.  Test firearm was a Contender with a 8.4” barrel in 44 Magnum and a 10” barrel in 45 Colt.  A 2.5X scope is on the Contender.  All measured data except group size (ctc widest shots) was obtained via the Oehler M43 PBL.  I had prepared 10 cases, as previously posted, for each test string; 10 with standard flash holes and 10 with the flash holes drilled out with a #28 drill.  Winchester WLPs were used in all cases for both cartridges. 

Testing was conducted from the bench with a Hoppe’s Pistol Rest with the target at 50 yards.

Temperature was 80 degrees.

Humidity was 30%

Barometric Pressure was 29.63

44 Magnum;

Bullet was a 429360 cast of COWW +2% tin, AC’d and aged 10+ days before sizing .430 and lubed with BAC.

Cases were Remington R-Ps sized and loaded in RCBS dies.

Powder charge; 22 gr of Alliant 2400

OAL; 1.638

With Standard flash holes;

Velocity; 1622 fps (muzzle)

SD/ES; 13/41 fps

Pressure; 35,800 psi(M43)

Pressure SD/ES; 500/1,700 psi

Group;  3.1”

 

With flash holes drilled;

Velocity; 1599 fps (muzzle)

SD/ES; 17/47 fps

Pressure; 34,500 psi(M43)

Pressure SD/ES; 1,400/3.900 psi

Group; 3.2”

 45 Colt:

Bullet was a 452-230-TC cast of COWW +2% tin, AC’d and aged 10+ days before sizing .454 and lubed with BAC.

Cases were CBC 45 Colt sized in RCBS steel FL sizer and loaded in Hornady dies.

Powder charge; 7.3 gr 700X

OAL; 1.598

LMG

Concealment is not cover.........

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John Carlson posted this 27 November 2023

I did a fouling shot article a few years ago, 30-06, 03A3, don't remember specifics but, conclusion was that enlarged flash holes eliminated protruding primers/shrinking headspace, improved chronograph data slightly, but I could not identify any effect on accuracy.  Tested in 3 different rifles with Remington brass married to each rifle.

John Carlson. CBA Director of Military Competition.

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Wm Cook posted this 27 November 2023

Thanks again Larry.

I have, indeed, used numerous other cartridges of various calibers from using LR primers with the flash holes drilled out.  The end result has always been the same; excellent ignition with less powders position "sensitivity"'

This is relevant to what I'm working on and what I asked in the opening post.

I’ve been working on a project to see the equivalency of SR primed .308 brass to LR primed .308 brass.  The initial effort compared LR Lapua with a .079 flash hole to SR Lapua PALMA brass with a .059 flash hole.  Comparing LR/.079 flash hole to SR/.059 flash hole is not comparing apples to apples.  As I’m about ready to embark on incrementally enlarging the flash hole size I thought I would throw out a shout to see if anyone has been down this path before.  Thanks, Bill Cook.

This is a good project.  First drill out the .059 Lapua Palma brass flash holes to .093 and do a head to head LR & SR to do the SD/ES comparison.  Probably using 2400 v 4895.   That'll help (at least a little) answer whether SR could replace LR in the .308 case.  Then I'll look at the slower burning rifle powders (example Varget, N135) with their LR to LR with their flash holes drilled out (example .111) to see if it effects SD/ES.  To date my work with standard Lapua LR brass with .093 flash holes using Varget & N135 didn't look promising.  I'm curious to see if I get a better, more consistent burn rate with a larger flash hole.

As a side note.  I'm not saying that low SD, minimal ES will = accuracy greater than combinations that may not look as good on paper.  At 600 yards it would but not so much at 200yds.  But I think its a valid test of the power burn rate.  Don't know if this is a controversy in the cast world but I believe that accuracy is based on barrel harmonics. 

While my initial focus was on whether the SR primer replace the LR primer in .308 brass the way the thread shaped itself it became a similar question but from a different perspective. 

"Can you use the flash hole diameter as a variable to effect powder burn rate +/-  to the % of case capacity actually used?"

A .308 case charged with 28 grains of powder fills the cast about 55% for me.  30 BR's in jacketed BR they are running loads with ~35g of 4198 and the 30BR's in Cast BR are using N135 at ~29g.  I'm just guessing, because I don't load 30BR, is that the case utilization on the Cast BR side is about 85%???  If I remember right Bud had said his 32-20 case capacity was about 70% and those cartridges shoots some screamers. Bottom line for me is that I don't think a more uniform, more consistent burn rate would ever hurt my accuracy.

MP, sorry but I totally missed the point you were trying to make.  Bill C.

Patience isn’t a virtue, it’s a delay tactic.

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MP1886 posted this 27 November 2023

So let me ask you Larry are you talking just using squib loads or are you talking high end high pressur jacketed loads?

On the shotshells I was referring to the factory experimenting with different size holes in the end of the large primer.  On muzzle loaders I was referring to the touch hole on flintlocks and the nipple hole on percussion cap firearms. I know what the percussion cap nipple hole does if you enlarge it.  On the Ruger ROA's the inside hole of the nipple is extremely small compared to other manufactures. Little story on that.  One castboolet member has/had a ROA and he was shooting Bullseyes powder in it.  I told him that won't work as  the cap doesn't get enough flame inside the cylinder to light off that Bullseyes. That's when he told me he drilled them out.  Not to worry though on what he's doing as I've read what Ruger did to test those ROA's and I won't repeat it in an open forum. Those Revolvers are quite strong to say the least.  But anyways back to what you were doing. I don't shoot a lot of squib loads have no use to drill out the flash holes. 

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Larry Gibson posted this 27 November 2023

"So let me ask you Larry are you talking just using squib loads or are you talking high end high pressur jacketed loads?"   

My post addresses the effect of the size of the flash hole in cartridge cases in cat's sneeze/low end pressure loads, "normal" pressure cast bullet loads and high pressure jacketed bullet loads. 

The OP, Wm Cook, made it perfectly clear he was discussing the size of flash holes in 308W cases and their effect on efficiency of ignition.  You might want to read his first post.  Thus, your discussion of shotgun shells and muzzle loaders neither adds information to or proves anything  but is simply not relevant to the OPs intended discussion as there is no 308W case used with the powders he mentions in your discussions.   

However, if you have meaningful data regarding the OPs actual topic we'd like to see it?  Otherwise, along with Wm Cook, I also miss your point.  

LMG

 

Concealment is not cover.........

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Larry Gibson posted this 27 November 2023

Wm Cook (Bill)

I've found no indication the size of the flash hole alters the burn rate as such as evidenced by no real change in the psi or time pressure curves.  I think what you're really seeking with the reduction of the ES/SDs is an increase in ignition efficiency which the measurement of those should address that.  I can also add additional confirmation because when measuring the psi of each shot in a test string the M43 also gives and ES/SD of the measured pressures.  Lower and more uniform ES/SDs of the pressure also gives a better measurement of the efficiency of ignition and burning of the powder (not to be confused with "burn rate").

LMG

Concealment is not cover.........

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Wm Cook posted this 27 November 2023

I think what you're really seeking with the reduction of the ES/SDs is an increase in ignition efficiency which the measurement of those should address that.Lower and more uniform ES/SDs of the pressure also gives a better measurement of the efficiency of ignition and burning of the powder (not to be confused with "burn rate").

That is exactly what I am trying to figure out.  I may be guilty of a false bias but I think that asking for a consistent, efficient ignition of the powder in a case that is half full of various compositions of medium rate rifle powder is asking a lot.  Again, I greatly appreciate the time you took to point me in the right direction.  Bill C.  

 

Patience isn’t a virtue, it’s a delay tactic.

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MP1886 posted this 27 November 2023

Don't get riled Larry.  We're just a group of guys throwing around ideas.  That's how people discover and learn things.  I reread what you have posted and now understand where you are coming from. My comments didn't have anything to do with the subject on hand here.  I just want to say that I'm sure when they design a case, for anything, that they take the flash hole size in mind. Here's an idea for you that you could save money.  Buy yourself one of those new fangled air rifles and have cheap fun. 

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Bud Hyett posted this 27 November 2023

"I've found no indication the size of the flash hole alters the burn rate as such as evidenced by no real change in the psi or time pressure curves.  I think what you're really seeking with the reduction of the ES/SDs is an increase in ignition efficiency which the measurement of those should address that."  

I concur that the small ES/SD is what we are seeking.

My research, empirical, started many years ago with a Savage 110S and R-P Benchrest .308 Winchester brass. With reduced loads of Reloder #7, three out of ten rounds had a hang-fire. And the hang-fires were noticeable in that the delay was apparent with a click-bang, not a lengthened firing sequence. My first step was to clean the inside of the bolt and lightly lubricate it. Still got hang-fires. 

This lead me to shoot full pressure loads with jacketed bullets for a contrast, using both Reloder #7 and IMR 3031, with Remington 7 1/2 and Federal Small Rifle Match primers. No hang-fires with these loads. Next I repeated these loads in nickel Federal Match brass also with no hang-fires. 

Realizing a meaningful structured experiment would involve several hundreds rounds shot under the same ambient conditions, I elected to shoot Large Rifle primers in big cases (.308 Winchester and larger) and Small Rifle primers in small cases. The exception is the 7mm BR since I can only find Small Rifle primer cases.

My expereince suggests I shoot Large Rifle primers in .308 and larger cases. The collective expereince above also says to me that we should shoot the cases as manufactured. If you can find  R-P Basic cases and want to shoot Small Rifle primers, more power to you.

Farm boy from Illinois, living in the magical Pacific Northwest

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Larry Gibson posted this 28 November 2023

MP 1886

Not "riled up" at all.  You're correct in that your comments had nothing to do with the topic at hand.  Have to disagree with the idea "when they design a case, for anything, that they take the flash hole size in mind".  Having studied, researched and measured flash holes in many cases over the years I've come to the conclusion "they" just use whatever size of hole their machinery is set up to produce.  That machinery probably has a +/- specification to it but that's about all the difference.  Probably because "they" long ago that a variation in the size of the flash hole doesn't matter with normal loads for the cartridge.  

It is where we use reduced or cat's sneeze loads that the size does matter.  That is more than evidenced from Bud Hyett's previous post.  Interesting to note on that subject is I've experience hang fires in some cases that were converted to SR Boxer primers from large rifle Berdan primers sch as the 303, the 7.65 and the 7.62x54R.  With the powders Bud mentions (RL7, 3031 and 4895) hand fires were encountered with the use of those SR primed cases.  The use of a dacron filler, however, negated the problem and ignition is positive and consistent with those powders using reduced cast bullet loads.  Ignition is also consistent with very fast burning powders such as Bullseye and Unique w/o a filler.  

Actually, I have 4 air rifles already [two 117s, a .20 and a .22] but they are so like last century as they are "springers".  That makes them more cheaper than them "one of those new fangled air rifles" cause all I need are the pellets and not tanks, pumps, etc.

LMG

Concealment is not cover.........

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