8mm Confusion

[glowe]

I need some help if anyone out there is reloading 8mm Mauser ammunition. We should be talking S&W, but I recently picked up a Gewehr Model 1898 Mauser, made in 1918 and found that it had the "S" stamp on the barrel, supposedly assuring me that it takes the larger .323 bullet. It has a .791 (.313") stamped on the receiver, which should be the bore. It is also known that the bore diameter of the Mauser was increased around 1905 to accept the .323 bullet.

I measured the grooves of the rifle at the muzzle and got .324. I then pushed a 32 S&W bullet through the bore and got a bore diameter of .315. That makes sense since the grooves were supposed to be .005, adding up to .325.

What I also believe as true is that the bullet should be the dimension of the grooves, while the bore is usually only the caliber identification and not the dimension of the bullet. I have read through several Forums and only get more confused because I think some people get bore and land dimensions confused when sizing bullets.

Many People on other Forums say that a .315 bore means the rifle takes a smaller bullet and shooting a .323 would be dangerous. Any thoughts would be welcome.

 

[DWalt]

If you have an 1898 Mauser, it will use the "S" (spitzer) bullet, 0.323" dia. The only 8mm German military rifle (to my knowledge) which used the smaller .318 bullet was the Model 1888 Commission rifle, and there were also some German sporting rifles chambered for the smaller diameter bullet. Many of the Model 1888 Commission rifles were converted during WWI to use the "S" bullet by simply enlarging the chamber throat diameter slightly to allow case neck expansion to release the bullet. The bore diameter was unchanged. That worked fine, as the S bullet just squeezed down when it was fired.

 

[Ivan the Butcher]

Rest assured, a barrel from 1918 is going to use .323 bullets!

When I first got into reloading (circa 1979), old German 8x57 ammo from batches with hang fires, was much cheaper than a box of Hornady reloading bullets. It was amazing how ammo from WWI & WWII and dozens of different factories made bullets that weighed within 3/10 grains of each other, even in time of war! (I weighed boxes of Hornady bullets, that weren't that close from the same box!)

The Germans & Austrians were obsessive about their guns and ammo! Much to our benefit today!

Ivan

 

[Fishinfool]

Gary, you should be fine using the .323 bullets. Bullet diameter should be the same or close to the actual grove diameter, especially with jacketed bullets. The tops of the "grooves" (lands) will be of smaller diameter, as the lands are supposed to engrave the bullet a certain amount, so as to prevent the bullet skipping over the rifling, and destroying accuracy. A good example would be the .44 mag., using a .429 bullet in a usually .429 groove diameter barrel. If the bullet were sized to say .424, based on your .005 land height example, then the smaller bullet would suffer from severe gas cutting around the bullet, as it would be riding on top of the lands, as well as probably poor accuracy.

Larry

 

[2152hq]

I have a couple of the Sporting rifles built by Haenel on the 88 action. These are in 8mm Mauser but the earlier version using the .318d bullet.

A check of the groove dia of the bbls confirms that.
I don't worry what the rifle bbl's 'bore' dia is (accross the lands),,it's the accross the groove dia of the bore that you are concerned with
.
These sporters are generally the older .318d (in 8mm Mauser) as are the orig GEW88 Commission rifles.
(German sporter bbl markings often show the caliber in m/m by the bore dia of the bbl,,not the groove dia. This also leads to confusion when reading this and interpretation.
For example an 'S' bore 8mm may show a caliber stamping of 7.91mm x 57mm.
The 7.91mm is the bore dia of the bbl. The 57mm is the case length.
7,91mm = .313"
add the .005" depth of rifling on each side (.010) and the groove dia (bullet dia) is .323.

They changed the bullet to the to the lighter spitzer style from the heavy round nose of the .318 to get an increase in velocity.
That is the 'S' version of the 8x57'.
Actually many of the other 8mm metric rifle calibers have both a .318 and .323 bulleted version,,8x60,,8x64 Brenneke, ect..

If the rifle bbl groove dia measures .323d, then it's the later 'S' version,,the common Military 8x57 round or Germany in WW1 and WW2.
These rifles and carbines will measure .323/.324 accross the grooves in a standard mfg bbl.

As DWalt says,,many of the GEW88 rifles in .318 bore were simply chamber modified, the neck opened up,,to allow the 'S' ammunition to fire in them safely. Stamped with a 'S" over the chamber to signify the modification.
The bores are still .318. So a .323 'S' bullet sizes down into those .318 bores each time.
Some I'm told were rebbl'd later on w/Czech mfg bbls in 8x57. Those later arsenal made bbls might just be 'S' groove .323. Seems logical but I really don't know the history of those Military 88's and their widespread use after the German's discontinued using them.

I use .321 Winchester Special bullets to load in my 8x57 .318 bbl's Haenal Sporters. The light loads I feed it and the very thin jacketed bullets offer no problems. I would never shoot 'S'.323 ammo or even reloaded ammo w/ those 'S' bullets in them.
They are just range toys and being old, I treat them with that kind of respect.
Cast bullets are often the best for these elderly rifles built on the M88 action IMO.

 

[DWalt]

Some years ago, I was the proud owner of a very high condition Model 1888 rifle. I bought it an estate sale for, as I remember, around $50. From the stampings on it, it appeared to be Turkish (the Germans provided the Turks lots of military equipment during the WWI period, as the Turks were Germany's allies). It had the "S" stamped on the front receiver ring, indicating the chamber had been modified to use the 8mm "S" round. I was at first a little hesitant to fire it with some WWII German 8mm military ammunition I had, but I did, and it didn't blow up. I fired probably several hundred rounds through it before I traded it off for another toy. I once removed the outer barrel jacket, and was surprised by how skinny the actual barrel was. I never understood why the "Commission" decided to use a barrel inside an outer metal jacket, and still don't know.

 

[Ivan the Butcher]

Barrel inside a Jacket.

I had a Belgium Champlain, single shot (copy of a High wall sort of), in 7x57 that was a jacketed/sleeved barrel. Even with the 24 pound trigger it was incredibly accurate. Most likely because of no bedding issues, and the jacket stiffened the barrel too.

The ammo for that era was long for weight round nose bullets with a full metal jacket (often coated steel on English sporting ammo). 215 grains for the 8x57J and JR; 175 grains for the 7x57; 160 grain for 6.5mm's like Mannlicher and Carcano; and 220 grains for 30-40 US and 30-03 Springfield. These bullets have very high Sectional Density, which gives them very good stability and penetration. And that is why all of those cartridges saw lots of use in Afrika in the 20's and 30's. The lighter Spitzer bullets had better Ballistic Coefficients and flatter trajectories but much less penetration (you don't need 25" for hunting people!)

The "worm in this apple" is the 8x56R Hungarian, it uses a 230 grain .333" diameter bullet of Spitzer boat tail design on the old Mauser "A" rimmed case. It was supposed to be the best of everything, but never liver up to the dream! The only other production cartridge in this diameter is the 318 Jeffery, using a 250 grain Round nose bullet soft point or solid. It was a very good Medium bore rifle by African standards, but didn't do well on the tough skinned big 4. (It did do well on big cats though!)

It gets a little confusing when there are 3 different 8mm diameters.

Ivan

 

[glowe]

Thanks guys. Before I bought this rifle, I was sure of what it was and what it shot, then as I researched the gun, I started finding many posts on various gun forums stating that a .315 bore should not shoot standard "S" .323 bullets. Too bad so many people give bad advice and just plain inaccurate information. The good news is that I see only comments that support my original premise about the gun. I also have a sporterized 1942 K98 and reload quite a bit, so have the brass, the bullets, and the powder to get me out to the 2000 meter max setting on the rear sight. Now all I need is to find somewhere to shoot 2000 meters! This one is an all matching German made rifle sent to Turkey.

 

[DWalt]

There is (sort of) a parallel for the U. S. .30 caliber military ammunition. As most know, the first .30 military round used by the US military was the .30-40 Krag (aka, the .30 U. S. or .30 Army). While it used a (nominal) .308" bullet, the Krag barrel diameter was made slightly oversized, about .310-.311. It was not noted for its good grouping capability. The Krag's receiver was poorly designed, and in addition to its problems in rapid reloading (which became evident in Cuba, where it faced the clip-loading 7mm Mauser used by the Spaniards) it was also relatively weak, and it was operating at about its upper limit of pressure with the standard .30-40 Krag cartridge. Attempts after the SPAM War to improve the ballistics of the .30-40 failed because of action cracking failures. As the Germans initially did with the 8x57mm (which had a 227 grain FMJ-RN bullet), the bullet adopted by the U.S. military was a 220 grain round nose jacketed bullet at a MV of around 2000 ft/sec.

As a result of the SPAM War, a new Mauser rifle design was adopted by the U.S. in 1903 (essentially an Americanized Model 98 Mauser, the Model 1903), but the same 220 grain RN jacketed bullet was retained, but in a larger cartridge case, the .30-'03, allowing a higher MV (about 2300 ft/sec). It took awhile for it to soak into the heads of U. S. Army Ordnance Corps that it was a ballistically poor choice to use a 220 grain FMJ-RN bullet (which the Germans had figured out earlier, as did the Swiss). So in 1903, the 220 grain bullet was dropped and a 150 grain spitzer bullet adopted, at a MV of around 2700 ft/sec. That was called the .30-'06 cartridge and it gave better accuracy (especially at long ranges) and much better ballistics than the .30-40 or the .30-'03. For ballistics reasons, it became necessary to change the chamber, resulting in the need to shorten the barrel by about 1/4" (the .30-'06 case having a somewhat shorter case neck), and most of the then-existing M1903 rifles were so-altered. This also had the effect of making the .30-'03 cartridge unusable in the shortened barrels. In summary, the Germans knew more about how to design both modern smokeless powder rifles and their ammunition that did the U. S. Army.

 

[MichiganScott]

Nice rifle. As an accumulator of military rifles, I've been looking for a very good condition full length Gewehr Model 1898 for years.

 

[rwsmith]

Such an impressive....

Such an impressive array of knowledge that can be found here.