The R is for Rimmed, both of these cartridges are the Rimmed equivalent of the 8X57 Mauser:

8X57 JS is the WWI and two German military cartridge diameter .323

8x57 J was the original Mauser caliber .318

None of them cans be shot in a 7X57 which is a .284 caliber.

Even if you reduce the neck of a 8X57 to .284 you will not be able to shoot it in a 7X57 chambered weapon because they don't have exactly the same shape.

Hope it helps.

P.L. PETIT

quote:

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Originally posted by JK:
What are the differences between the 8x57 JR, 8x57 JRS, and 8x57 JS? Is anyone of these actually a necked-up 7x57 mauser? Thanks, JK.

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The original 8x57I (I= Infanterie) was constructed for the german M88 rifle, and had a 220 grains bullet in .318", if I don�t remember falsely. Ten years later the famous M98 was constructed and the M88/ 8x57I cartridge was used for that too.

In the first decade of the 20th century, the germans considered the M88 cartridge with 220 grains bullet too slow, and constructed a new, lighter bullet with torpedo shape. For the planned higher velocities the old M88 .318" barrels had too less rifling to give any accuracy. The grooves had to be cut deeper and the bullet slightly fatter.

The new diameter of the bullet was .323", and the cartridge was called 8x57IS, where the "S" indicates the new measure. The "S" is mostly read as "Spitzengeschoss", but another opinion is "Standard". As metric barrels usually are measured between the lands, the was no change in caliber, which was still 8 millimeter. It is also called "8 mm Mauser".

"R" indicates a cartridges with a rim, or in german "Rand". The 8x57IRS and 8x57IS are identical in shape except the rimmed base.

I would rather call the 7x57 a down-necked 8x57I. In any case you can use 7x57 cases for loading 8x57 and vice versa. Other cartridges based on the 8x57 are 5,6x57, 6,5x57, 9x57, 9,3x57 and the obsolete 6x57 and 10,75x57. Most of these have their rimmed brothers.

Yours,

Fritz

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

You are wrong, these cartridges don't have exactly the same profile, the shoulders are not exactly at the same place and the base diameter is slightly different, this is valid for the rimmed ones too.

I own these cartrodges and the differnces are clearly visible.

Take a look at Ammoguide to see the differences:

http://www.calweb.com/~haas/ammoguide/runammo.html

P.L. PETIT

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

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'Trapper'