Plain Based/Gas Check Question Military Loads CE Harris Work

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  • Last Post 22 December 2009
kokojoe posted this 18 October 2009

I have read C.E. Harrris' work “Cast Bullets for Military Loads” and an extensive post from 1994 on the 7.62 x 39.  Both are absolutely excellent and have helped me immensely.

For those interested, here's one link:

http://home.comcast.net/~gavinsw/guns/castbulletmilitaryrifle.pdf

I am working on casting and loading for the SKS and the Mosin 91/30.

I use the #2400 powder recommended in his writings.

All has worked well to this point.

I could not leave well enough alone, however, and got the Freechex to make the aluminum gas checks because I was nearing the end of my on-hand Hornady supply.  With .011 material up to .014 (for which they were designed), the aluminum checks are a little lose when sized on from .311 to .314 compared to the Hornady copper check with thickness of about .017.  So, I tried to ream out the Lee C312-155 gas check on the mold to have a more firm grip on the aluminum GC.  Well, I messed it up.  So, I'm going to have a “professional” friend ream it on out to create a plain base C312-155 mold with a .3125 base.

I ordered a new mold to deal with the GC again.

Harris' work did talk about some reduced loads with the Lee bullet and no GC.

So, before I get to experimenting, I'd like some ideas and input on this creation for shooting the plain base C312-155 out of the SKS and 91/30 with the #2400 (or other recommendations).  What loads should work without leading?  I have a sample pack of White Label lube - will some of those lubes help with these?  (I've used the traditional 50/50 to this point).  Will the base (that used to be the gas check) help seal the bore and prevent leading with increased loads?  I'm thinking of not sizing and just using a .314 die in the sizer to lube this.  Should I ream the mold base to .313 if I can rather than .3125 (I just know I've got the .3125 reamer on hand)?

I've been able to identify leading in my pistol barrels easily  - but not sure that the rifle barrels will be as easy to do so.  Any hints on that?

Thanks

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runfiverun posted this 18 October 2009

thats a lot of q's right there. for the plain base boolit i'd change to a bit faster powder and target a slower velocity <12-1400 fps> the larger base isn't a bad idea as your bbl may be this big anyways. your friend could make your 313 base with your 312 sizer actually. i know it don't make sense ask him about it. as far as the g/c's go you will have to try the new mold first and do the math as to what you need. one of the greatest shortcuts with cast is to measure first then figure out what you need to change to make things work for you. glens lubes are really good lubes i have used the 50-50 mmixed 2-1 with his red to make a bac type lube for quite some time, and it does well in rifle applications.

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Ed Harris posted this 19 October 2009

For plainbased bullets in 150-180 grain range with current Alliant Bullseye and standard large rifle primers DO NOT EXCEED:

5.0 grains in the 7.62x29 6.0 grains in the .30-30 7.0 grains in the .30-40 Krag, 7.7 Japanese, 7.65 Argentine. 308 Win., or .303 British 8.0 grains in the 7.62x54R,  .30-'06 or 8x57mm DO NOT INCREASE these loads, they are maximum for a plainbased bullet. RECOMMEND REDUCING ALL LOADS 1.0 GRAIN TO START.

OK to increase 1.0 grain ONLY with GC bullet.  

 

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

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kokojoe posted this 19 October 2009

Ed Harris wrote: For plainbased bullets in 150-180 grain range with current Alliant Bullseye and standard large rifle primers DO NOT EXCEED:

5.0 grains in the 7.62x29 6.0 grains in the .30-30 7.0 grains in the .30-40 Krag, 7.7 Japanese, 7.65 Argentine. 308 Win., or .303 British 8.0 grains in the 7.62x54R,  .30-'06 or 8x57mm DO NOT INCREASE these loads, they are maximum for a plainbased bullet. RECOMMEND REDUCING ALL LOADS 1.0 GRAIN TO START.

OK to increase 1.0 grain ONLY with GC bullet.  

  Thank you, Ed.

In the rimless 762x39 - does the flash hole need to be sized bigger per your article? I did not completely understand that but will try to read it again. You said the rimmed, such as 54R, would not need that.   Is the Alliant 2400 comparable to the Bullseye for these load?

Would a higher BHN, such as by heat treating into the 20's, increase the potential load?

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Ed Harris posted this 19 October 2009

With these charges of Bullseye you don't need to ream flash holes. In bottle-necked cases you can try it as a refinement, to prevent shortening the head-to-shoulder length of larger cases, but you have to be careful to keep that brass separate and not use it by mistake for full loads. In the 7.62x39 pressure is high enough that this isn't a problem.

Harder alloy is of no advantage because you don't want to load Bullseye higher than about 25,000 psi in any case, and wheelweight alloy is about correct for that.

 

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

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kokojoe posted this 19 October 2009

Ed,

Is Bullseye not “position sensitive"?  This is one of the positive features of the 2400 you mentioned in your article for the full loads.

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cityboy posted this 20 October 2009

Ed Harris wrote: With these charges of Bullseye you don't need to ream flash holes. In bottle-necked cases you can try it as a refinement, to prevent shortening the head-to-shoulder length of larger cases, but you have to be careful to keep that brass separate and not use it by mistake for full loads. In the 7.62x39 pressure is high enough that this isn't a problem.

Harder alloy is of no advantage because you don't want to load Bullseye higher than about 25,000 psi in any case, and wheelweight alloy is about correct for that.

 

I get around shortening of the case by spraying a silicon lube on the cases. I get my spray at Wal-Mart. I have been doing this for years with good results. Try it, you will like it.

Jim

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kokojoe posted this 20 October 2009

Forgive me, but I am new at this.  What causes the shortening of the case and how does the lube prevent it?

My guess is that the low charge does not put enough pressure to hold the case to the chamber and it is forced back against the breach?

Thanks

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kokojoe posted this 21 October 2009

Ed,

I've got a C312-155-2R that I messed up the gas check shank on.  I was thinking about milling off the surface to eliminate the gas check.  I cut the gas check off of one bullet and it weighed in at 120-130 grains.

Do you think this would be a worthwhile experiment for a plain-based 120-130 grain bullet for the reduced loads?  Or do you think the flight would be poor?

Thanks

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cityboy posted this 26 October 2009

kokojoe wrote: My guess is that the low charge does not put enough pressure to hold the case to the chamber and it is forced back against the breach?

Thanks

You are correct. The impact of the firing pin and the pressure buildup in the primer pocket drives the case into the chamber shorting the case. As pressure builds up the case is driven back toward the bolt face. Without lube on the case, it begins to stick to the walls of the chamber. When the pressure is low, the case will not stretch back to its original length.

jim

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kokojoe posted this 27 October 2009

I tested a 130 grain boolit with 5.3 grains of W231. I found that the gas leaked “back” - so the neck of the case was fouled and I could feel the “poof” of air back through the breach.

Should I increase the charge to avoid this, is it ok, or should I examine for some other problems?

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Ed Harris posted this 27 October 2009

kokojoe wrote: I tested a 130 grain boolit with 5.3 grains of W231. I found that the gas leaked “back” - so the neck of the case was fouled and I could feel the “poof” of air back through the breach.

Should I increase the charge to avoid this, is it ok, or should I examine for some other problems?

That charge is a bit light for a 130-grain bullet.  As an approximation only, with 231 you can increase about 20 percent over a known Bullseye charge to get close to the same velocity.  So, probably 6 grains of 231 in the 7.62x39 should be OK. Above that you are on your own, as I haven't tested it. 

If cases have been reloaded repeatedly so that the neck and shoulder has work-hardened, then re-anneal the cases and this will also help.

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

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kokojoe posted this 27 October 2009

Thanks, Ed, I'll up that a bit.  I forgot to mention it was in the 762 x 54R - so, I'll try 6-8 grains of W231.

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Ed Harris posted this 27 October 2009

Yes 6 grains would be correct in the 7.62x39, and 8 grs. if good in the 7.62x54R. Would not be afraid to try 9 grs. of 231 in the 7.62x54R if the plainbased bullet doesn't lead. Have used as much as 13 grs. in the big Russian with a 162-grain GC bullet, similar to the red Dot load.

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

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kokojoe posted this 27 October 2009

Thanks, Ed.

I used your recipie on the 155 grain plain-based with #2400 and it worked fine. 

I'll try the W231 in the 130 grain.

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linoww posted this 27 October 2009

I shoot the plainbase Pope Ideal 308403 in CBA Military matches with 7-8 of BE or 10-12 of Unique.with decent luck.It been good enough to shoot 90-95's on both the 100 and 200 yd targets.Not match winning,but cheap<G>I only differ from other PB shooters in using a fairly hard alloy of WW and stereotype mixed.

George

"if it was easy we'd let women do it" don't tell my wife I said that!

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Dicko posted this 22 December 2009

I think I might be a bit more conservative about light rifle loads with handgun powders.  Bullseye is a fast powder even for handguns.   In my 308 Win I use the equivalent of Unique.   The charges are still low and economical but a bit safer in my humble opinion.   I shoot the Lee 180 grain 30 cal bullet.   In 12% antimonial alloy ( about as hard as linotype ) it weighs 166 grains plain base and 170 with gas check.   For plain base, 10 grains gives 1400FPS with no leading, 13 grains gives 1600FPS with very little leading.   At 1800FPS leading is unacceptably heavy.   I also have some results for S265 powder which is similar to 2400.   20 grains = 1750FPS.   26 grains = 2130FPS.   The rest were linear progression between those.

You can regard 1600FPS as the practical limit for plain base because of leading above that.   With gas check you can fire cast bullets almost at jacketed velocities.   I have fired the same bullet at 2400FPS using S335 (similar to 3031) with no leading.

I suspect that I can push the S265 and S335 loads further but I'd rathervremain cautious until I have had them pressure tested.

Sure, gas checks don't always fit nicely, usually because moulds vary.   Making them from a thinner material will worsen that.   Remember that the OD must be big enough for calibre.   If the material is thinner the bullet base must be bigger.   The proper solution is to bore out the mould to the right diameter for the gas check.   Easier said than done because it is a cut and try issue.   I have not had to do it yet but the time is surely coming.   Easiest way is to turn a plug from aluminium.   Turn it down until a gas check fits nicely.   The plug then becomes the plug gauge for boring out the mould. 

In any case you should slug the barrels because military groove dia can vary a good bit.   They are often bigger than spec.   Most SMLEs are nearly all bigger, typically one to two thou bigger.   Then your gas checks and sizing die must suit.   You might have to polish out a die if you can't get one.   I recently enlarged a 311 die to 313 for that reason.  

 

 

 

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