.311 or .323 bullet for Yugo M.24/47?

[propstrike]

Hey all,

Quick question if I may. I have a Yugoslav 24/47 in 8MM Mauser. The import markings from CAI signify that the caliber is 7.92mm patrone 98. The rifle is in excellent shape and the muzzle mikes out at .311 on the lands. I have heard that 7.92 is the same as 8mm Mauser, which is a .323 bullet. Does the Yugoslav or other ammunition use a slightly narrower bullet? Or is it ok to use the Mitchells Mauser ammo, and other commercial, like Wolf, or PMC?

Cheers,

propstrike

[Mosko]

Yes, the 7.92 caliber marking is the same as the spoken "8mm" Mauser. 7.92 or 8mm, is the grooves measurement approximately. The "lands / bore" measurement will be smaller than the dia of the grooves, which is what you mention in your post. Slugging the bore will provide something to measure the grooves by.

I'm not familiar with your particular rifle, but it very well could have been bored .311, then the rifleing cut .006 deep from there, making the groove dia .323".

[propstrike]

Danke Shoen, Mosko! Clears the whole issue---shoots great with Yugo surplus, so I may just stick with that. Lately, I have seen a lot of these M24/47 rifles on the market, must have been imported recently.

Cheers!

[Mosko]

I like the Yugo surplus 8mm ammo myself. I fire Hakim's and FN-49's. I have damaged both in the past firing the Turk 8mm. The Yugo is nice and mild, and very easy on the rifles. Also I don't remember ever having a hang, or miss fire with the Yugo like I have some of the others.

[Rockman]

The Commission 1888 Mauser had a bore of .318", not .311" no "Modern" Mauser's were .311", those were British and Jap rifles, the 7.7 is still .311" too. I agree with Mosko.

[Mosko]

Remember, the M1888/05 Commission rifles, "S" marked were modified with a new bore for the spitzer projectile measuring .323. We mostly call them "Turked 88's" around here. From a distance they look the same. Firing 0.318" projectiles in the /05 is not a safety problem per se, but the .323 in the .318 standard 88 is, or could be.

[Rockman]

Mosko, Thank you for clearing up my mix up, my apologies. I knew one was smaller but did not know one it was exactly. :grinning-thumbsup:

I gather this is why the Remchester ammo is downloaded so badly, kind of like a "gallery round" with a 170 gr. projectile and not too much more power than a .30-30?

Also, I noticed when I use commercial ammo in any Mauser that is in the .323" / 7.92mm caliber, I need to slide the rear sight up to 200 meters to get a bullseye at 100 yards.

[Mosko]

I haven't done any scientific tests or anything, all I have is my perception, but I have noticed the commercially loaded 8mm Mauser being "weak" myself.

I think it's a liability issue with the commercial loaders. There are so many old rifles out there chambered in the 8mm Mauser, some of questionable steel quality etc, that they must be down loading that round to be more safe "generally".

Naturally, I wouldn't have any real idea of how many, but I'd bet a large number of folks who acquire and "old rifle" marked 8mm Mauser, simply go by wallmart, buy a box or two of the commercial stuff, and fire away, without any other consideration at all!

[Rockman]

I see what you mean Mosko. I think it might be out of fear that somebody or a group of folks might have some of the Commission 1888's with the .318" bore and the comm. people might down load their ammo for safety reasons.

[Bob S]

You won't find a Gew 88 with a .318 "bore". The bore dimensions of most European arms were specified by the bore diameter, and a groove depth. The bore diameter of the original Gew 88 barrels were 7.9mm nominal, with a groove depth of 0.1mm. That would make the groove diameter 8.1mm nominal. If you do the math, the bore diameter was 7.9/25.4, or .311"; and the groove diameter is 8.1/25.4, or .3189". The nominal bullet diameter of the Geschoss 88 was also 8.1mm or .3189". If you have ever seen an original pre 1891 Gew 88 barrel, you would swear it was made from drawn seamless tubing ... the walls are very, very thin. This was the dawn of the smokeless age, and the pressure of the early '88 ammunition could be very erratic. Put that together with sloppy tolerances in both bullet and barrel manufacture, and a barrel that is only marginally capable of holding the design pressure, and there were problems with burst barrels. The first "fix" was in January 1891, when the external dimensions of the barrels were beefed up. Rifles fitted with such barrels were marked with a dot about 1mm in diameter on the top of the receiver ring, above the maker's mark. This still didn't totally fix the problem.

In 1896, the Germans' did extensive studies with internal dimensions, and decided to increase the groove depth to 0.15mm. Bore diameter remained at 7.9 nominal. The internal dimensions were then .311" bore diameter, groove diameter (7.9+0.3)/25.4, or .3228". The bullet diameter remained at 8.1mm, or .3189". Rifles with altered barrels, or new barrels made to the new dimensions were marked with a 3mm letter "Z" over the chamber.

The S-Patrone cartridge that was adopted by Germany in 1903 had a bullet diameter of 8.22mm, or .3236". The neck f the cartridge case was correspondingly bigger also than the old Geschoss 88. Ludwig Olson has a side-by side pic of the two cartridges, and the difference in neck diameter is readily seen with the naked eye. Attempting to fire one of the new cartridges in the old barrels usuaklly resulted in diaster. Some Gew 88's were modified by re-reaming the chamber and throat to give sufficient clearance for the neck to expand when firing the S-Patrone cartridge. That is the only modification: it was an expediant only, and a poor one, as the bullet of the S-Patrone is still too big for the Gew bore/groove, and the cartridge generated pressures that could damage the Gew's. Only barrels with the "Z" mods received this new chamber. Barrels with modified chambers were marked with an "S". Somewhere the myth started that the Gew 88 "S" marked rifles were "rebored" for the S-Patrone cartridge and bullet, but they were not: they were only rechambered.

The picture is a non-Turk 1894 Steyr, "S" marked. The recoil lug has cracked from continued use of S-Patrone ammunition.

http://img.photobucket.com/albums/v76/BobS1/G88crackedlugA.jpg


The only Gew 88 variants with barrels that are truly sized for the modern S-Patrone or Ss-Patrone (196 grain) are the 1935 Turkish variants without the barrel guard in the pistol grip stocks. These have essentially the same barrels as the Turk M1893 conversions. IMHO, the Gew 88 action is just too weak to shoot any S-Patrone or Ss-Patrone surpluys ammo or clones. Mild handloads with appropriately-sized bullets will be much kinder to the rifle, and will be more accurate. The only way to determine the "appropriately-sized" bullet is to do a chamber cast to include the first inch or so of the bore, and then slug the bore with a soft lead slug and mike it. All of the barrels you are likely to find will be four-groove, so it is easy to accurately determine the groove diameter. I have six Gew 88's, two Gew 88/05, and one Gew 88/s, and they all mike between .311 and .312 bore, and between .3205 and .3215 in the grooves. I have two Turk M35's, and both are .312/.324. (The Gew/s is not to be confused with the "spitzer" marked chamber (although it does have the mark) ... this model was a WW I mod that used the original Manlicher clip, but it had a floor plate to keep the mud out of the action, and a coil spring on the floor plate that would pop the clip out the top when it was empty (instead of it dropping out the open bottom as on the original rifle) ... just like an M1. Very trippy!!!

Speer makes a 170 grain "flat point" .321 bullet that is really a semi-point with just enough meplat to prevent popping the primer of the next round in a tubular 32 Special magazine. The bullet is probably the best choice for the Gew 88 that I have found, besides cast bullets. It can be seated to full magazine length and feeds reliably from both the mannlicher clips and from the magazine of the 88/05 mods.

These rifles are a pleasure to shoot and will shoot accurately, as long as the bore is not raoched, and you craft ammunition to fit your rifle.

Resp'y,
Bob S.