Gew 88 Low Pressure - Should I Bump It?

[Joshua M. Smith]

Hello,

My load for the Gewehr 88 with a bore that slugs 0.318" is as follows:

Winchester case formed from .30-06 Winchester case

0.318" 150 grain spitzer bullet

46.5 grains Varget

Federal large rifle primer

Now, I'm having signs of gas leakage around the neck. I'd like to bump it up a little bit to make that stop, but it's probably due to the "S" rethroating.

I don't remember the upper limit for the 7,92x57J cartridge, or for the rifle. I was thinking 40,000PSI, but am not sure.

I was going to start bumping it a grain at a time, but I'm really not sure when to stop. I know that by the time it shows pressure signs I'll be dangerously exceeding the action design.

I'd love me a pressure gun, but since I don't have one, I'll have to take educated approximations from you all.

So, where do you suppose I should stop?

Thanks,

Josh

 

[rcmodel]

I think you should stop where you stopped with that old action.

Hodgdon shows 45.5 grains / 150 .323" Hornady giving 37,500 CUP.
SAAMI spec is 35,000 PSI.
So 46.5 grains should place you right at the pressure limit and then some.

You could perhaps get a better gas seal by annealing the case necks to make the brass softer.

rc

 

[NCsmitty]

I think you should stop where you stopped with that old action.

+1 on that statement.

Germany's first smokeless powder military rifle was fraught with problems and several modifications were needed to address the issues.
Pushing the envelope on the pre-98 metallurgy is probably not a good idea. IMO, low pressure cast bullet loads are the safe way to go in these old rifles.
If you want a shooter, get one of the 24/47 or M48 Yugo rifles that are designed to take the higher pressures of the 8x57JS ammo.


NCsmitty

 

[DaveInFloweryBranchGA]

And you can find out a bunch more about what NCSmitty is talking about over on the Cast Boolit forum. These gentlemen have given you great advice.

 

[Joshua M. Smith]

Thanks folks.

I figured I was approaching the pressure limit, and really just trying to establish a new upper limit.

I really do like where I'm at.

I'm mainly a handgun handloader and someone once told me that any leakage around the mouth of a rifle cartridge was a bad thing.

I really don't care as long as it's not dangerous. The case body seals it off and I get no blowback in my direction.

I'll stick with where I'm at.

Thanks!

Josh