I have a nicely engraved German or Austrian 98 Mauser. on the left side of the front action ring its marked 2.7g G.B.P. and under that is ST.M.G. can anyone tell me what these markings indicate?

standard marking.

G.B.P. stands for Gewehr Blättchen Pulver (rifle flake powder).

St. m. G. means Stahlmantel Geschoss (steel jacket bullet)

thanks much, and the 2.7g would equate to 42 grs. of German Flake powder, and probably the test load according to Bobster on another thread.

One more question, the markings 8x57J followed by nich for S are telling me it is a .232 bore, 8x57JS, I am assuming "nick stands for made? and for some reason was a later stamp, and the rifle was made soon after the change from .318 to .323 in 1920..Just my guess?? so this barrel is a 8x57JS?

The coversion from J to S was simply opening up the chamber throat to accept the larger case neck and bullet. The bore is still .318.

You can safely fire .323 bullets as long as they are Spitzer style of 198 grains or less (standard WWII ammunition).

You can not use heavy round nose 220 grain bullets of .323 diameter. Use .318 if you need that heavy of a bullet.

2.7 grams of Military flake powder is about 41.5 grains of smokeless powder.

I thought nich was NOT. Although I have fired lots of Ss ball (323) ammo in Commission 88 rifles that had been modified in the chamber only.

"8x57J nach S" would make more sense, if that is what is stamped.

Yes that would mean "to S". Nich doesn't mean anything that I know.

Ok, now I'm confused as to what I could shoot in this barrel! and what the markings are and mean.

It is marked 8x57J then skips a few spaces and it is marked clearly "nich for S"

nich means "nothing", "made", or "not" according to emails and posts..it isn't marked "nicht" it is "nich" ?????????

I would normally just rebore the barrel to a 9.3x62, except the rifle is mighty light at about 5.5 lbs and that would be verging on brutal recoil, and the 9.5x57 has never interested me much..

Its just a really nice old rifle and it great condition except no original barrel, and I have had this 8x57J for several years. I also have a NIB old 25 Rem. barrel for and Enfield and those big threads could be cut for a LR Mauser, and that would be something different and pretty neat, but the barrel may be worth more than the gun?

You really should slug the bore and measure it. Take a lead round ball larger than .323 and smack it into the muzzle with a plastic hammer. Push it out and mic it.

"nicht" is german for not. Could be a warning, like the safety paragraph on today's firearms.

The bore has nothing to do with it. A .323" spitzer bullet will go down it no problem. 8mm bores are all over the map, from .317 to .325.

You need to do a chamber cast. The difference between a J and S cartridge is in the neck and throat.

When an older rifle was converted to an S, they simply ran the S reamer thru the chamber. However, the S stands for Spizter. You have to use Spitzer style bullets, because they have a minimal bearing surface. You cannot use heavy round nose or solid bullets unless they are .318"