which 8mm ammo do i use???

S

SAA GunSlinger

New member
so I recently purchased an old ww1 Gewehr 98 made in Danzig 1902 but I know that there are two different type of 8mm. 8mm Mauser "R" or 8x57JRS - .318 bore (which is actually 7.92mm) and 8mm Mauser "S" bore, 8x57 JS, 7.92x57mm JS, etc. This has a .323 inch diameter bullet. The rifle has an "S" stamped on the barrel which from my understanding means its chambered in 7.92mmx57mm JS. Can I safely shoot modern 8mm mauser and or surplus 8mm from 40's and 50's?
 
I know that there are two different type of 8mm. 8mm Mauser "R" or 8x57JRS - .318 bore (which is actually 7.92mm)
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Nope. "R" means rimmed. So you can have an 8x57JR .318" or an 8x57JRS .323" as called for by your drilling or other break action or falling block.

The rifle has an "S" stamped on the barrel which from my understanding means its chambered in 7.92mmx57mm JS. Can I safely shoot modern 8mm mauser and or surplus 8mm from 40's and 50's?
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An "S" stamped on a 1902 vintage Mauser may well mean that it was converted from J to S after the 1905 changeover from .318" roundnose to .323" spitzer. The conversion was done by reaming the chamber neck to clear the larger diameter cartridge neck-over-bullet and cutting a long tapering leade into the rifling so a .323" bullet would be gradually swaged down to .318-.320" for the rest of the barrel. This was an expedient to get some use out of the 1888 and early 1898s in WWI.

Most American 8mm is based on the old Remington Special load which is very light with a soft 170 gr bullet meant to be reasonably accurate in the S bore and safe in a J bore. Full power European ammo, whether fresh or surplus is a good bit hotter. Maybe somebody here will post on its suitability.

Your Danzig might have been rebarrelled, it would pay to slug the bore.
 
A military 98 will not be set up for 8x57R.

What he needs to know is the groove diameter so he can select the right rimless round.
 
"...which is actually 7.92mm..." It's not(7.92mm converts to .311".), but that doesn't matter. An 'S' bore is .323". The 'S' stands for Spitzer.
The 'JRS' is/was a rimmed .323" bullet commercial hunting version of the 8mm Mauser cartridge. The M/88 ,used in the Model 1888 commission rifle, used a 226 grain, .318" RN bullet.
 
At one time, the conventional designation was 7.9 for the .318" J bore and 7.92 for the S bore. Have to remember, they were going by bore diameter, not groove diameter or bullet diameter. 8mm is just a convenient single digit.
 
That is bullet diameter, close to groove diameter.
Caliber designations were typically by bore diameter.
I realize the distinction has been lost to much of the Internet Generation, but it does matter.
See also 7.62mm which is .300", which as a bore diameter can be rifled for anything from .308" to .311" and more often found larger rather than smaller.
 
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All discussion of bore diameter aside, the Gwr 88 which has an "S" on the front of the receiver was intended to be shot using the 'updated' 8mm round of 1905. That was the loading of a 154 grain (more or less converted from gram weight) at around 2880 with the original thirty inch barrel.

So most any 8x57mm round should be okay, presuming it is loaded to standard military levels. Most modern U. S. ammo is loaded much lower due to some confusion about action types. U. S. commercial ammunition should not push one at all.
 
But I don't think they were intended to be shot a LOT. Not only were the spitzer bullets somewhat larger diameter, they were also loaded to higher pressure. Didn't most of the converted 88s go to garrison and support troops? By the way, they didn't just ream the neck and throat for the larger bullet, they also converted them from enbloc to stripper clip loading.
 
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