Powder coated bullets: What max velocity can be run and what BHN required to do it?

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  • Last Post 13 March 2024
JimGnitecki posted this 07 December 2023

1. At how high a muzzle velocity can you launch a powder coated cast bullet (following load tables of course)?

2. What BHN is needed, or optimal, with the high velocity?

I am asking these questions because in an effort to improve trajectory, to delay transonic effects, and to improve bullet stability, I tried increasing velocity by shooting 405g commercially cast, conventionally lubricated bullets, at 1500 to 1600 fps velocites.

The results were bad: no grouping whatsover right from the first group fired, and sure enough, when I checked the barrel condition afterwards, I had, for the first time ever, lead fouling of the barrel, and a LOT of it. It took me 1.5 hours to get it out via chemical and patching and brushing.

This is despite the fact that I had been shooting 464g to 500g powder coated bullets at up to 1400 fps with NO leading whatsoever. In fact, only unburned powder fragments in an otherwise pristine barrel. Those 464g to 500g powder coated bullets actually produced groups as good as 0.8 MOA at 150 meters = 164 yards. But, that's a s fast as the load tables will allow, so if I want to go faster (and I do), I need to know how fast powder coated bullets can be driven and what BHN constraints, if any, apply.

So, I am wondering if I could get a mold that produces a lighter weight bullet (say 400g or thereabouts), powder coat the those bullets, and launch them at the higher velocities that the load tables say are permissable and achievable with those lighter weight bullets, and see what accuracy I can get.

The usage would be purely paper target and steel gong targets. NO hunting, so expansion or brittleness don't matter.

Jim G

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Spindrift posted this 08 December 2023

I can't give a precise answer to your questions, but I can relate my experiences with PC bullets in mostly bottle- neck "modern" cartridges;

1) There is no well-described upper limitation to muzzle velocity. With gas checked PC bullets, jacketed bullet data often works fine in for instance .308win.

With PC plain based bullets, I have achieved excellent accuracy in a 1:10" ROT 30-06 at 2050fps. When your load exceed the tolerance of the system, accuracy deteriorate in a more gradual fashion than lubed bullets.

2) alloy requirements... hardly worth worrying about at the conditions you describe. Bhn 15 PB bullets grouped better than BHN11 bullets at 2050fps from a 30-06, though. So alloy is not completely irrelevant- but you have so much more tolerance with PC. I would just choose an alloy that you have in good supply.

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JimGnitecki posted this 08 December 2023

Thank-you, Spindrift. That gives me a good starting point. Your comment on the BHN 15 vs 11 makes sense too. In his book "Modern Reloading", Richard Lee said that for best accuracy, the bullet psi strength should be proportional to the handload's peak pressure, and ideally about 10% higher than peak pressure.

Jim G

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mashburn posted this 10 December 2023

With PC gas checked bullets, I start at the beginning jacketed loads and work up.

Mashburn

David a. Cogburn

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JimGnitecki posted this 10 December 2023

With PC gas checked bullets, I start at the beginning jacketed loads and work up.

Mashburn

 

You use the JACKETED starting loads with pwoder coated gas checked bullets? I did not know you could do that safely. Is the gas check required or optional when using jacketed loads with pwoder coated bullets? (My mold is a plain base mold).

 

Jim G

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mashburn posted this 10 December 2023

You have to use a gas check. Other than in handguns, I don't shoot plain base bullets. Go with Spindrift's info, He is the man who got me started.

ALL POWDER COATED BULLETS ARE NOT EQUAL. A powder coated bullet that is not coated properly cannot be driven as fast as a bullet that is properly coated.

Mashburn

David a. Cogburn

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tomme boy posted this 11 December 2023

Hardness still matters the faster you go. Once up over 2K it shows its ugly head just like regular naked bullets. But not as bad. I have shot my 223 past 3Kfps but accuracy was not even close to jacketed. But slowed them down to 2700fps and I could keep them into 1.5" groups. Slow it down to 2400fps and most were right at 1". 

 

My 223 I still shoot for 15-19 for hardness. My 350 Legend I shoot for 12-15. I run these up to 2100fps. My 7.62x54 I use the same as the Legend and I run a 215gr at 2000fps 

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mashburn posted this 11 December 2023

I have run the velocity of my .17 Mashburn up over 3,100 and have had great accuracy, but like you said, it depends on the bullet, the cartridge and the rifle. Also, referring to my statement in a previous post in this thread, ALL POWDER COATED BULLETS AREN'T EQUAL. I see pictures of powder coated bullets, that people post and then claim that powder coating doesn't work. 

Mashburn

David a. Cogburn

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JimGnitecki posted this 11 December 2023

Thank-you, Guys! My powder coating quality is pretty good I think, and I do not see any need to go beyond 2000fps with my planned 400 grain .45-70 cast bullets, so it sounds like I should be ok. Keep in mind that I have already successfully run the 464 to 500g .45-70 bullets at up to 1400 fps with my powder coating, so a 400g powder coated bullet at 1600 fps should work without leading.

That is encouraging, and after all my only modestly successful efforts with the heavier bullets, the 400 grain bullet class gives me a fresh start.

Jim G

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ray h posted this 11 December 2023

Mr Mashburn,  What is the 17 Mashburn, made by necking the 22 Mashburn Bee down? Are you using the the Noe 25 or 32 gr bullets. What are you sizing the bullets for a .172 barrel. Who's coating are you using and how thick is it.?  Thanks

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Lee Guthrie posted this 12 December 2023

Just curious what rifle(s) you plan on shooting 400 grain bullets at 2,000 fps in a 45-70 chambering.  

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JimGnitecki posted this 12 December 2023

Just curious what rifle(s) you plan on shooting 400 grain bullets at 2,000 fps in a 45-70 chambering.  

 

I do realize that to respect the 28,000 psi pressure limit  on the Pedersoli Sharps replica rifle, and the relevant load tables, a 400g bullet can only be fired at 1600 fps maximum. However, if 400g class bullets do not give me the accuracy I want, I will then try lower weight bullets which can presumably be loaded to a higher muzzle velocity (I have not yet checked to see HOW fast a, say 300g bullet, could be launched.

 

My interest is in shooting this buffalo rifle replica at long ranges. So, I need as high a velocity as I can get in order to keep the combination of trajectory, wind deflection, and transonic effects manageable. The "2000" fps is simply what online trajectory calculators indicate would give me sufficient velocity to reasonably efeffectively balance tarjectory, wind deflection, and transonic effects. If 2000 fps turns out to be "not enough" to realize these objectives, it's time to make the target a larger gong versus a small bullseye.

Jim G

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mashburn posted this 14 December 2023

Hello ray h

The .17 Mashburn was one of Mr. Mashburn's ideas, who owned and ran Mashburn Arms in Oklahoma City. Every improved or Wildcat Cartridge that he originated seemed to have one purpose, and that was to outdo P.O. Ackley It is based on a .218 Bee Case, but the neck is only .172 long with a 40- degree shoulder angle, and has only about .002 body taper. The case capacity is almost identical to a .17 Mark IV. I have never been able to find any information on this cartridge in any loading manuals, including Wildcat reloading books. I got a hold of his shop made reamer for this cartridge along with three other reamers for his cartridges. I have built rifles cambered in calibers of these reamers.The first .17 caliber rifle that I ever saw was a .17 Mashburn. That experience took place in 1962, when I was 18 years old, and I've been a .17 caliber fan ever since. The funny part is, I married the daughter of the man who showed me the .17 rifle and cartridge. I met her while her dad and I were shooting rifles. Bye the way, we're still married.

 

I shoot the NOE 25gr. and when gas checked and powder coated, they weigh 27.3 grs. and bullets are 001 over bore size and I think my coating is .0025 approximately. Don't hold me to that figure, I haven't shot it, in almost four years.

When shooting jacketed bullets, it preferred the 20 grainers over the 25's accuracy wise, but I lost so much clean killing power with the 20's when prairie dog shooting that I always shot 25's.

I would like to find out more about this caliber, if anyone out there knows of any information, such as books please let me know. I know it exists because I got my reamer from his shop and I saw one in 1962.

Thanks for your interest,

Mashburn

David a. Cogburn

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Buttersdad posted this 17 February 2024

I have been contemplating these same questions and soaked up the info. My question is what powders are yall using with these cast powder coated loads? Are they the powders listed with the jacketed loads in the tables?

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Spindrift posted this 17 February 2024

I tend to choose single- based extruded powders among the faster of the listed powders. I'm not saying you can't get good results with slower powders (you can), but it's a good place to start.

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Buttersdad posted this 20 February 2024

Thanks Spindrift. All of my rifle bullets are cast, gas checked and powder coated. I have a good supply of smokeless powders and would like to use the listed powders in the tables. Does the same advice stand, " start with the start charge and work up"?

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Spindrift posted this 20 February 2024

Yes, you may start with the listed starting load, and work up. Sometimes, when the powder in question happens to respond well to a slight load reduction, I start a little below the listed starting load. Relatively fast- burning stick powder often tolerate this well.

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Buttersdad posted this 21 February 2024

Thanks Spindrift. I don't have any trouble with published loads but I have gotten on this train a little later than many. I'd heard that PC'd, GC'd cast could be pushed to these velocities but couldn't find much on smokeless powders used. Good to have this info.

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2frogs posted this 22 February 2024

All very interesting. My question is how do you know your have a good powder coating? Mine look good to me.. thanks

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Buttersdad posted this 10 March 2024

Mine look good to me also and I as yet have no transfer of powder coat or leading in my barrels. My plan is to start low with these powder charges and work up slowly checking my pc quality at each stage,

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JBinMN posted this 10 March 2024

2frogs posted this 3 weeks ago

 

All very interesting. My question is how do you know your have a good powder coating? Mine look good to me.. thanks



2frogs,

    Not really a "scientific" method, but it has been suggested that one does a "Smash Test" to one or more of the PC'd bullets after they have cooled.

You simply take one of the bullets & smash it flat with a hammer.

If the PC stays stuck to the alloy, then it is acceptable. If it falls off/flakes off/no longer adheres, then it is likely that it is under-baked/cured, and was not at temp long enough to fully adhere to the alloy.

I have done this test & found that it seems to work. For me and others who try it anyway.

I have shot under - baked/cured PC'd bullets before I knew about the "smash test" when I first tried PC-ing, and when I shot the under-baked/cured and not knowing it, the bullets left streaks of PC in my barrels and it was a Real Hassle to get it out. Worse than leading, to me. This was in handgun bbls, I can only imagine how it would be in a rifle bbl.
Did I mention that it is a REAL Hassle?   Believe me, it is. Worth repeating. Don't shoot under-bake/cured PC'd bullets.

It frustrated me enough trying to get that PC out of those barrels that I almost gave up completely on PCing cast bullets. But I stuck to it anyway, figured out what I was doing wrong & went back at it.

I have since found that I actually prefer to tumble or pan lube more than I do the PC route, but the option is there for me to do any of them should I choose to do so.

G'Luck~!

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Brodie posted this 13 March 2024

With PC gas checked bullets, I start at the beginning jacketed loads and work up.

Mashburn

 

You use the JACKETED starting loads with pwoder coated gas checked bullets? I did not know you could do that safely. Is the gas check required or optional when using jacketed loads with pwoder coated bullets? (My mold is a plain base mold).

 

Jim G

There is really no reason not to Jim, people have been using  Jacketed data to start with paper wrapped lead bullets and smokeless powders for a long time.  It either works or it doesn't.  It will not blow up the gun.  You can work up from there until accuracy begines to degenerate.

B.E.Brickey

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MP1886 posted this 13 March 2024

Brodie is 100% correct about the paper patch.

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