K-98 Mauser ammo question,,,

aarondhgraham said:

I'm embarrassed that I don't know this already.

Is 8mm German Mauser ammunition also called 8 x 57?

Aarond

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Yep!
Also called 7.92x57 in certain circles

Also 8x57 IS or 7.92x57 IS. All different names for the same caliber.

Both 8mm and 7.92 are technically correct; the barrel grooves of the German Mauser rifle are 8mm in diameter, and can theoretically accommodate a bullet of this size. But the typical bullet is actually 7.92mm in diameter.

If your rifle was manufactured after 1905 it is 8x57JS and shoots a .323 diameter bullet. The older 8mm Mauser was a .318 diameter bullet. American ammunition makers load all 8mm mauser rounds to specs that can safely be shot out of both diameters. If your rifle is the JS, which it probably is, look for European ammo as they load it to its potential. The American 8mm ammo is loaded around 30-30 velocities where the Europeans load similar to 30-06 ballistics.

Both 8mm and 7.92 are technically correct; the barrel grooves of the German Mauser rifle are 8mm in diameter, and can theoretically accommodate a bullet of this size. But the typical bullet is actually 7.92mm in diameter.

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I'm fairly certain that the BORE diameter is 7.92 mm (@.312") and the groove diameter is 8.2 mm (@.323").

I could be wrong on this, but that's my understanding.

I have a bunch of old Winchester .321", 170 grain Silvertips that are marked "8 mm" (I think they were actually intended for the .32 Winchester Special). In any case, the reduced diameter, coupled with the SAAMI max 8 mm pressure of 35,000 PSI (cup?) would probably make them reasonably safe to fire in an unconverted '88 Commission Rifle, I wouldn't recommend it, but that was apparently SOP at one time and may still be.

aarondhgraham,

If that 400 round crate is mil. surplus , and chances are great that it is , it will in all likelihood have corrosive primers. If so, clean your rifle asap accordingly after use.

Strictly speaking, 8x57 (I or IS or J or JS) is the civilian designation. The WWII German military used the designation 7.9, which is the bore diameter of .311". The groove diameter of .323" is 8.2 mm. Like many cartridge names, "8mm" is an approximation - 8mm is actually .315" which is only nominally correct for any dimension.

In spite of what has been written, Model 1888 rifles, which had the same bore diameter but a .318" groove diameter, were converted to use the larger .323" bullet, but they were not re-rifled; the only change was to enlarge the chamber neck to the new dimensions.

Jim

Originally posted by Jim K

In spite of what has been written, Model 1888 rifles, which had the same bore diameter but a .318" groove diameter, were converted to use the larger .323" bullet, but they were not re-rifled; the only change was to enlarge the chamber neck to the new dimensions.

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I've never heard that before (my understanding was that they'd altered the chambers and had their rifling recut to .323), but your explanation actually makes a lot of sense.
What I've read in the past is that SAAMI keeps the 8mm pressure levels so low to prevent damage to unconverted M88's (meaning those that hadn't had their rifling recut to .323).

That never made sense to me, because unless the rifle had an incredibly worn out chamber and leade (or if the shooter used turned case necks), it would be unlikely that a round with a .323 bullet would even chamber.

Could you please give me your source for this information? I'd like to read up on it.

geo57 said:

aarondhgraham,

If that 400 round crate is mil. surplus , and chances are great that it is , it will in all likelihood have corrosive primers. If so, clean your rifle asap accordingly after use.

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You should read up on cleaning it after using corrosive ammo. This is after all a family treasure and I would bet you are going to want to pass it down one day....I know some people that bring a bottle of windex to the range with them to hose it down. I have personally seen a barrel flash over with rust in as little as 4hrs on a hot humid Missouri afternoon.