8MM Mauser with 318 bore
- Thread starter benschott
- Start date
jds holler
Gold $$ Contributor
If it actually slugs out at .318, that's what I'd look for. Maybe cast and size accordingly. jd
Talk to Gmac.
When you say '0.318 bore', what are you referring to?
Both the original 7.9X57 I (often referred to as 'J') and the later (1905 on) 7.92X57 IS (or 'JS') share a common bore as defined by the bore (land to land) diameter which IIRC is 0.312" or similar. (Hence the 7.9 / 7.92mm calibre designations which equate to just under 0.312" using the common European convention of naming cartridges after their bore diameters rather than the US one of bullet / barrel groove diameters.)
The 7.9 I version uses 0.318" groove diameter, while the IS was enlarged to 0.323", originally by reboring the grooves only in existing 'I' form G1898 rifles in 1905, then by manufacturing all subsequent barrels to the 'S' form. Rebored military G98s had the letter S engraved on the front receiver ring when the modified barrel was refitted so there was no confusion about whether they could handle IS spec cartridges.
Both use bullet diameters to suit the groove diameter, ie 0.318/9 for the original ('I') version; 0.323 for the later 'IS'. The latter also used a lighter pointed bullet and was loaded to a much higher pressure.
What is the rifle? If military, the model should determine its barrel dimensions, although some M1888 ('Commission') rifles which were all originally built for the 7.9X57 I have been rebarreled / rebored to suit the later cartridge with larger broove diameter dimensions. Even so, the G1888 has a much weaker Mannlicher designed action than the later Mauser designed model 1898 receiver, and although such a modified rifle is fine with ammunition loaded with 0.323" dia. bullets, is a decidedly 'iffy' pairing to a full-pressure 55,000 psi IS model cartridge.
Many Portuguese M1904 6.5X59P military rifles were adapted to 7.92X57 IS in the late 30s when that country adopted the cartridge and purchased KAR98k rifles from Nazi Germany. This was done by shortening, setting back, rechambering, and reboring the 6.5 calibre barrels to full later 'IS' spec to handle the very potent 198gn bullet sS version of the 7.92 (schwerer Spitzgeschoss or heavy pointed bullet). Although also a Mannlicher based receiver design, these rifles happily handle full 7.92X57 IS pressures (but like the KAR98k, produce a nasty 'kick' from it). All FN manufacture, likewise Czech and Yugoslav manufactured military Mausers are 7.92X57 IS irrespective of the countries they were sold to.
The exception to the post-1905 rule can be German originating gunsmith built sporting rifles dating from before WW2, many surviving and some ending up in the US and British Commonwealth as wartime souvenirs from WW2. For some reason, many gunsmiths preferred the 'I' bore form and specified barrels with 0.318" groove diameter. Many are built on the lighter, but weaker small-ring M1893 Mauser action too, presumably for the weight saving.
Both the original 7.9X57 I (often referred to as 'J') and the later (1905 on) 7.92X57 IS (or 'JS') share a common bore as defined by the bore (land to land) diameter which IIRC is 0.312" or similar. (Hence the 7.9 / 7.92mm calibre designations which equate to just under 0.312" using the common European convention of naming cartridges after their bore diameters rather than the US one of bullet / barrel groove diameters.)
The 7.9 I version uses 0.318" groove diameter, while the IS was enlarged to 0.323", originally by reboring the grooves only in existing 'I' form G1898 rifles in 1905, then by manufacturing all subsequent barrels to the 'S' form. Rebored military G98s had the letter S engraved on the front receiver ring when the modified barrel was refitted so there was no confusion about whether they could handle IS spec cartridges.
Both use bullet diameters to suit the groove diameter, ie 0.318/9 for the original ('I') version; 0.323 for the later 'IS'. The latter also used a lighter pointed bullet and was loaded to a much higher pressure.
What is the rifle? If military, the model should determine its barrel dimensions, although some M1888 ('Commission') rifles which were all originally built for the 7.9X57 I have been rebarreled / rebored to suit the later cartridge with larger broove diameter dimensions. Even so, the G1888 has a much weaker Mannlicher designed action than the later Mauser designed model 1898 receiver, and although such a modified rifle is fine with ammunition loaded with 0.323" dia. bullets, is a decidedly 'iffy' pairing to a full-pressure 55,000 psi IS model cartridge.
Many Portuguese M1904 6.5X59P military rifles were adapted to 7.92X57 IS in the late 30s when that country adopted the cartridge and purchased KAR98k rifles from Nazi Germany. This was done by shortening, setting back, rechambering, and reboring the 6.5 calibre barrels to full later 'IS' spec to handle the very potent 198gn bullet sS version of the 7.92 (schwerer Spitzgeschoss or heavy pointed bullet). Although also a Mannlicher based receiver design, these rifles happily handle full 7.92X57 IS pressures (but like the KAR98k, produce a nasty 'kick' from it). All FN manufacture, likewise Czech and Yugoslav manufactured military Mausers are 7.92X57 IS irrespective of the countries they were sold to.
The exception to the post-1905 rule can be German originating gunsmith built sporting rifles dating from before WW2, many surviving and some ending up in the US and British Commonwealth as wartime souvenirs from WW2. For some reason, many gunsmiths preferred the 'I' bore form and specified barrels with 0.318" groove diameter. Many are built on the lighter, but weaker small-ring M1893 Mauser action too, presumably for the weight saving.
Adam in WI
Practically lives here
I have to question the logic behind this. Knowing that there is a chance that not every rifle will be updated to the newer specifications; wouldn't it make more sense to make the modern high pressure variant smaller in diameter? This should in theory reduce the risks of firing the later ammunition in the earlier bore, and vise versa...
absolutely correct. totally impracticable...I will forget this rifle and move on, thanks Adam.
Adam in WI
Practically lives here
I was only speaking from a large scale military standpoint. If you have a chance to pick up a clean '88 Commission rifle, I'm not sure I would let that opportunity slide. Cautious loading practices can make it an enjoyable piece of history. Just don't fire European spec JS ammo in it. Even US spec ammo is held to low pressures for the chance that it gets fired in a .318" bore.
cast lead is your only cheap shooting ammo . There are manufacturers and special runs of 318 jacketed bullets .
Look for a ‘ S ‘ stamp at the rear of the barrel , possibly under the wood line . This could ( should ) indicate an eenlarged throat to allow 323 bullets . It’s basically just freebored to reduce pressure.
Very few ww1 mausers were not modified, the only ones I’ve seen are nice german hunting rifles .
Look for a ‘ S ‘ stamp at the rear of the barrel , possibly under the wood line . This could ( should ) indicate an eenlarged throat to allow 323 bullets . It’s basically just freebored to reduce pressure.
Very few ww1 mausers were not modified, the only ones I’ve seen are nice german hunting rifles .
sneakboxer
Silver $$ Contributor
I have not personally tried this but what about Lee sizing dies? I know they are for cast bullets but it seems plausible. https://leeprecision.com/bullet-sizers-punches I read somewhere about guys taking .366 bullets down to .358. Best of luck
thanks for a MOST informative post. this Mauser 98 rifle had been sporterized by J.P. Sauer before WW1. I sure will be looking for the "s". thanks again.
I found bullets and ammo at Reeds. Excellent service. contact them at; www.reedsammo.com
Laurie,
Didn't Louis Schlegelmilch do most of the work on the bolt? The Commission "borrowed" Mannlicher's loading system, hence OEGW Steyr getting the rights to sell the Commision rifle commercially. But I didn't think Mannlicher had any direct role in the German version.
You're a historical research step ahead of me there, Tim.
CH still makes reloading dies for the 8x57mm Mausers firing a .318" projectile. As far as I know they are the only ones currently doing so.
Liven The Dream
Gold $$ Contributor
Will just for information.
Many years ago I was a great 98 Action Nut.
I made many a fine Hunting Rifle from them.
Case in point Mauser Banner Action 98 with Barrel. Condition AAA ? inside the barrel looked like a Grenade went off. .318 Barrel
This was a Mauser Contract Rifle markings on Receiver pointed to Ethiopia .
Many years ago I was a great 98 Action Nut.
I made many a fine Hunting Rifle from them.
Case in point Mauser Banner Action 98 with Barrel. Condition AAA ? inside the barrel looked like a Grenade went off. .318 Barrel
This was a Mauser Contract Rifle markings on Receiver pointed to Ethiopia .
Replacement .323 barrels on Flea Bay
Yugoslavian (Zastava) M48 - M24/47 Mauser Barrel - Cal. 7.92x57mm | eBay
Original Yugo Mfg. (Zastava) Unissued/New Surplus M48 - M24/47 Mauser Barrel - Cal. 7.92 x 57mm. Fully threaded. Radius crown. Price shown is for ONE barrel. Multiple depicted to display variations of condition.
www.ebay.com
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