I keep reading about 8x57 "JR", "JRS", and "IRS" cartridges. Are these all a classic 8x57 Mauser with different rims? Is it just a designation difference for the type of bullet loaded?

What is an 8x75RS? Is it a smaller 9.3x74R?

THANKS!

The JR bore diam. is generally" .318, although may reach .321. The JRS bore diam. is .323

The way I understand it is that the J and the I are interchangeable, just different interpretations of the old German alphabet. "S" is for the newer .323 groove diameter bore, with no "S" groove diameter is .318 or so. Teh S was added when bore size was reduced and the German military changed to Spitzer (pointed) bullets. Case dimensions are identical on all cases marked 8x57, except that the "R" of course designates Rimmed.
The 9.3 x 74R is a VERY different cartridge.

The "I" is really a German "J". So "I" or "J" mean exactly the same thing. It depends on who has written the box label or reference! There was originally only one 8mm Mauser. The "I" or "J" at 318".

Later when the Germans adopted a lighter bullet they found that they could get more velocity by making a pointed bullet ("S" for Spitzer) AND by increasing its base diameter to .323". So the these new cartridges were given an "S" in the name. No longer 8x57I (or 8x57J) but 8x57IS (or 8x57JS).

Thus 8x57 "IS" written as 8x57IS or (as I've said because the "I" and "J" are the same also seen as 8x57 "JS" written as 8x57JS).

So an "I" or "J" rifle uses 318" bullets and an "S" bore rifle uses 323" (or, at a pinch) 318" bullets. But NEVER "S" bullets in a "I" rifle!

The "R" means rimmed. So:

8x57J or 8x57I is a rimless 318" bulleted round.
8x57JR or 8x57IR is a rimmed 318" bulleted round.

8x57JS or 8x57IS is a rimless 323" bulleted round.
8x57JRS or 8x57IRS is a rimmed 323" bulleted round.

Both existed alongside each other. But gradually, like the 30-03 Springfield giving way to the 30-06 Springfield no more new rifles were made in 318" bore but only in 323" bore.

So by the time of 1914 and World War I the German Army's rifles were all 8x57IS (or 8x57JS - remember that "I" and "J" means the same).

To complicate matters further two newer cartridges were introduced later. When only the new 323" bore dimensions were being made in the factories. So when these new "improved" cartridges came out they were only ever loaded with the 323" sized bullet for those new barrels.

So you will see 8x64S and 8x68S also. But NEVER 8x64I (or 8x64J) or 8x68I (or 8x68J). They dropped/didn't use the "I" (or "J") from these cartridges as there weren't ever military, or "Infantry", Army rounds!

After World War I the defeated Germany was forbidden to allow its civilians to own any rifles in the military calibre. So that there could not be a "militia" I suppose with the ability to be supplied direct from Army ammunition supplies.

So sportsmen had to forfeit their sporting rifles in that 8x57IS (or 8x57JS) or have them demilitarised. This was done by reaming the chamber longer. So that if military issue cartridges were fired there would be dangerous headspace. The chamber was increased by three millimetres.

So its cartridge was called 8x60S (or 8x60S). You'll often see these in Europe.

Any rifles in the older 318" size didn't have to have that done.

Lastly, to complicate matters further! In some countries the 8x57 in either "I" ("J") OR "IS" ("JS") size is called the 7.92mm Mauser. And we British used a tank machine gun made in Czechoslovakia that fired that 323" bulleted round. The German Army round! But we British called it the 7.92mm BESA after where the machine gun was invented!

These 7.92mm BESA rounds are now all fired off. But in the 1970s I used to see them at auction in Britain. They worked absolutely fine in any 323" bore Mauser service rifle!

That "I" by the way means "I" for "INFANTERIE".

And, praise God, because only Germany had this messing about with changing from 318 to 323 you won't see such "I" or "IS" nonsense with any other European country and its 8mm rimmed or military sporting cartridges (8mm Lebel, 8mm Mannlicher aka 8x56, etc., etc.).

quote:

Originally posted by Sid Post:
I keep reading about 8x57 "JR", "JRS", and "IRS" cartridges. Are these all a classic 8x57 Mauser with different rims? Is it just a designation difference for the type of bullet loaded?

What is an 8x75RS? Is it a smaller 9.3x74R?

THANKS!

Sid:

These are all rimmed 8MM cartridges.

Germany adopted the rimless 8X57MM in 1888, chambered in the 1888 Commission rifle. The cartridge was designated "I" for "infanterie". This cartridge used a .318" RN bullet. In 1905 a new version of the cartridge loaded with a spitzer bullet was adopted. This version used a .323" bullet, and was designated "IS". Somewhere along the way in the nomenclature for these cartridges, the "I" was mistaken for a "J" and stuck, and these letters are still used interchangeably. Thus "IR" and "JR" mean exactly the same thing with respect to these German 8MM cartridges. If the "S" designation is absent (8X57IR or 8X57JR), bore is assumed to be .318". If it is present (8X57IRS or 8X57JRS), it is .323". The designation "R" means rimmed, thus 8X57JRS is the rimmed version of the 8X57JS.

8X57I or 8X57J = rimless .318"
8X57IR or 8X57JR = rimmed .318"
8X57IS or 8X57JS = rimless .323"
8X57IRS or 8X57 JRS = rimmed .323"

The I/J bores are loaded to lower pressures than the S bores, and the rimmed versions are loaded to lower pressures than the rimless, so don't assume that one is indicative of the others.

The 8X75RS is the 9.3X74R necked down to take an S-bore 8MM (.323") bullet, and is more powerful than the rimmed 8X57, 8X60, and 8X65 versions.
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"Serious rifles have two barrels, everything else just burns gunpowder."

AND the 8x57js is loaded to a max pressure of 57000 psi

The 8x57jRs (rimmed version) is only loaded to 48000psi max pressure.

Are the lower pressures due to a weaker action in the double rifles? Or does it just make extraction easier?

quote:

Originally posted by Sid Post:
Are the lower pressures due to a weaker action in the double rifles?

Yes. It's because the rimmed version is intended for use in drop-down barrel action rifles.
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"Serious rifles have two barrels, everything else just burns gunpowder."

Just bought an O/U in 8X57JRS. Nice round.

Beware of older guns in these chamberings. One would think that the use of .318-bore barrels ceased after WW1, but not quite so. I ran across a nice Buhag o/u DR in 8x57IR, and it was made as late as the mid-Fifties.