RE: 8mm
"8mm mauser JS which if memory serves me right is the low pressure stuff."
No, you've got this BACKWARDS! The JS (InfanterieSpitzgeschoss, or infantry pointed bullet) ammo is the round adopted by the Krauts in 1903. It was loaded with a lighter, faster, pointed bullet as opposed to the earlier round that used a 236-grain round-nose slug at a much lower MV (and pressure level).
FYI:
What does “8X57 JS” mean??
The "J" is an "I"! It means "INFANTRY" The "S" stands for "spitzgeschoss", or "pointed bullet". What happened was this:
The original Model 1888 German infantry rifle and the M98's, up to 1905, used ammunition with .318" diameter bullets-the original was called "8X57J". Strangely, (to our way of thinking) the actual bore diameter of these rifles was .322" to .323" despite the fact that they were shooting .318" bullets in them!! (Believe it or don't! Many early European smokeless powderrifles were shot with UNDERSIZED BULLETS!!) So, when the Krauts changed to the 154-grain POINTED BULLETS in their rifle ammo in 1905, they also started making the bullets full-groove diameter, (.323"), and called them "pointed", "spitzer", or "S" bullets.
To shoot this ammo with the bigger bullet in older rifles, they found some of them had to have the CHAMBER THROAT diameter reamed up a little over the previous dimesion so the case would freely release the bullet on firing. Rifles so altered were stamped with a big "S" on the receiver ring. Note that, contrary to some stories, the entire bore diameter of these converted "S" stamped rifles was NOT changed, because .322" to .323" was the dimension they had always been!
HOWEVER, many civilian-made 8X57mm rifles made during this era DID, IN FACT, USE .318" groove diameter barrels! These civilian "J" bore guns should indeed be used with .318" bullets only, but this caution does not apply to German military 8X57 "J" rifles that have altered chambers! (Some later manufactired COMMERCIAL 8X60, and other 8mm rifles as well, also had .318" rather than .323" bores. So ANY COMMERCIAL/CUSTOM barreled 8X57mm, 8X60mm, or 8X64mm, etc., rifle should be checked to see what the actual groove diameter is before firing!
For example, I have an 8X60Rmm J.P. Sauer double-barreled rifle that was made around 1912. It is marked "7,8 X 57R" under the barrels. This "7,8X57R" marking is X-ed out, and it is restamped 8X60R. The implication here ("7,8") is that this rifle is a .318" size. BUT slugging the barrels show the groove diameter of each to be .322", and the cases do release .323" bullets when fired, so I use them. This rifle was altered by rechambering in 1944 to 8X60R, but there was nothing done to the bores. It was merely rechambered to use the 60mm case, so it obviously had .322" grooves from day 1, just like the German military rifles.