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American Rifle
Rifle Magazine
February - March 2004
Volume 39, Number 1
ISSN: 0017-7393
Number 227
On the cover...
The Remington Model 700 Classic .300 Savage features a Weaver 4x scope in Leupold rings and bases. Photo by Stan Trzoniec.
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When self-contained metallic cartridges began appearing in the early 1860s, one thing quickly noticed was the buildup of powder fouling in the guns firing them. Revolver cylinders stopped revolving, cartridges refused to chamber fully, and accuracy was noticeably degraded.

At the time the only possible substitute for black powder was the various fulminates. (Remember the Volcanic repeating rifle and pistol, forerunners of the Henry?) These compounds were normally used in very small quantities in percussion caps and as priming compound in rimfire and later centerfire cartridges.

Use of fulminates as a propelling charge was never successful. Results ranged from poor accuracy to an entire magazineful of cartridges detonating at the drop of the hammer. Flying gun parts and wood splinters did nothing to enhance such ammunition’s reputation.

Something would have to be done because a new development demanded cleaner ammunition. By 1880 the invention of Dr. Richard Gatling was well known to the armies of the world. American association with the Gatling gun is probably best remembered for someone who could have taken a couple with him, but didn’t – a fellow by the name of George Armstrong Custer. It was later learned the general thought the Gatlings would hamper his mobility. Sioux warriors hampered it a lot more.

It was the British who really used the Gatling. Firing the .577/450 Martini-Henry cartridge, the gun was introduced to the Zulu in the late 1870s and the rest of Africa by the early 1880s. Make no mistake, those guns worked well but could be put out of service by fouling.

It was a Frenchman by the name of Paul Marie Eugene Vielle (also spelled Vieille) who led the way in solving the black-powder problem. What Vielle did was learn to control nitrocellulose, a combination of guncotton (cellulose) and nitric acid. The resultant wet compound was rolled into very thin sheets, cut into strips and then cut again into small flakes. Time frame was 1883-1884, with 1885 seeing production of a new propellant called Poudre B.

This new powder almost eliminated fouling, allowing bullet diameter to drop dramatically and still maintain adequate accuracy. Development of the machine gun began in earnest.

Not all citizens were happy, however. In most of the world at the time, everyone mistrusted everyone else. Only the French had smokeless powder. Only the French could use it in the new rifle and machine gun designs. A lot of folks didn’t like that much. Germany, which had been the winning side in the Franco-Prussian War, didn’t like it at all because it rendered its new 11mm black powder repeating rifle obsolete overnight!

There are many interesting stories regarding German response to the French development. It is known, for example, that a Lebel rifle and ammunition were in German hands before issue to French troops. Some say a deserter escaped with them thinking the Germans might be interested enough to part with a bit of gold for the privilege of owning them. Another story names the deserter as a German agent. Yet another states it was well known throughout Europe that a lot of money would be traded for knowledge of the new smokeless powder by various parties.

All the intrigue makes interesting reading, but in reality the simplicity of the process guaranteed it wouldn’t be a secret very long. Indeed, Germany was also working on such a powder by 1883 but was using wood as a source of cellulose instead of cotton. This didn’t work well. Thus by 1887, and probably earlier, Germany knew how to produce a smokeless powder reasonably close to the French product. All they needed was a little “help.”

When using the new propellant in an improved military rifle cartridge, however, the Germans and French went in different directions. French Lebel rounds were rimmed and quite large at the base – an aging design. Bullet diameter was .323 inch.

German planners realized there could be no doubt of the impact the machine gun would have on future military events. Smaller, lighter guns with improved feed mechanisms could be devised thanks to improved cartridges made possible by smokeless powder. Germany’s new cartridge would take machine gun thinking into account in no small way.

Diameter of the bullet of the new round was .005 inch smaller than the Lebel, or .318 inch. Unlike the fat, rimmed Lebel, the German case was narrower with no protruding rim. Instead the rim (obviously necessary for extraction of fired cases) was the same diameter as the case body above the rim. A recess for the extractor was machined into the case, thus forming the rim. Also, the case was bottle-shaped (larger diameter body that tapered down to hold the bullet by way of an angled shoulder) like the Lebel. Having no rim, however, the new case headspaced on the shoulder. Case length was 57mm. The new round was designated 7.9mm Patrone M88 (7.9mm Cartridge Model 1888.)

Origin of this case style is not German, instead generally credited to a Colonel Rubin, director of the Swiss Laboratory at Thun, Switzerland. Feeding in machine guns was a parameter. Rubin was using compressed black-powder charges behind bullets of 7 to 9mm in diameter in his experiments.

Case capacity of the German cartridge came to about 7 percent less than the Lebel. Nevertheless, ballistics were nearly identical. The Lebel used a 232-grain roundnose bullet at a published 2,060 fps muzzle velocity; the 7.9mm achieved 2,067 fps with a 227-grain roundnose.

Germany had in the 7.9mm M88 cartridge what was without doubt the best military rifle and machine gun cartridge in the world at the time. This did not mean it was without problems.

Many unanticipated glitches could only be discovered by using the round in the field and seeing what didn’t work. This occurred with the brass alloy from which the cartridge case was made. Early 67/33 percent copper/zinc alloy proved too hard, necessitating a softer 72/28 percent mix.

Next, inadequate neck tension allowed the bullet to become loose. Stab crimps were applied to the neck to remedy this, and eventually neck wall thickness was increased. Then case necks began cracking at the stab crimp marks. Finally, neck annealing such as used on case necks today was developed. As machine gun designs progressed, further strength problems with the case cropped up. All were solved by unseen changes to case wall taper or thickness.

Most widely debated is the variance of internal barrel dimensions and bullet diameters of early 7.9mm arms and ammunition. The topic often makes use of the terms J-bore, Z-bore, S-barrel, J-bullet and S-bullet. This writer has reviewed at least eight different explanations over the years and no two are exactly alike! Let’s look at a few facts, then see if we can figure out what was going on.

The first fact is that bore diameter (hole reamed in barrel before rifling) for the 7.9mm cartridge has always been 7.9mm (.311 inch). Why some call it an 8mm is unknown. The M88 cartridge used an 8.1mm (.3189 inch) diameter bullet (J-bullet). Rifling depth for the M88 barrel was 0.1mm (.0039 inch). Simple addition now reveals that barrel groove diameter (J-bore) and bullet diameter were identical at 8.1mm.

When M88 ammunition with its long, hard jacketed bullet pushed by the new smokeless powder was fired in these barrels, the rifling quickly wore away and barrels ruptured, split or just plain blew out in various locations near the breech. Such was not desirable. Failures were blamed on the bullet being too large in diameter, though erosive, unstable powder was more likely at fault.

As a remedy, rifling groove depth was increased from 0.1mm to 0.15mm. We now have a groove diameter of 8.2mm (.323 inch). Neither bore nor bullet diameter were changed. These barrels had a Z stamped on them (Z-bore). Gas leakage past the bullet stop­ped barrel blow-outs and deeper rifling gave longer barrel life. Remember, Germany was after better field results from the average soldier’s rifle, not smaller bench­rest groups.

When the 7.9mm S (Spitzgeschoss or pointed bullet) cartridge was adopted in 1903, its bullet was 8.2mm (.323 inch) in diameter (S-bullet), very pointed and only 154 grains in weight. Velocity is given as 2,930 fps. Smokeless powder employed was of a more highly developed type using deterrent coatings to control burning rate. Gas leakage past the bullet was no longer necessary. Bullets were shorter, which reduced jacket fouling and rifling wear.

New barrels on the strong Model 98 actioned rifles were chambered for the S-cartridge. Weaker Model 88 rifles having the larger Z-bores were rechambered for the S-cartridge by opening the chamber neck diameter and freeboring to further relieve pressure. These barrels received an S stamp (S-barrel).

If this isn’t confusing enough, military J-bore barrels were sold to private gunsmiths for many years. Riflemakers also continued to produce barrels having J-bore dimensions long after they were dropped by the military. Thus where they may show up is anyone’s guess. Any early sporter or Model 88 rifle should have its bore slugged before firing. Pushing a jacketed .323-inch slug down a .318-inch barrel could damage a fine, old rifle.

Soon after adoption of the 7.9mm S-cartridge, its cupro-nickel coated steel jacket was found to give excessive bore fouling in machine guns. The solution was to replace the cupro-nickel with Tombak, the German equivalent of gilding metal.

After a few years experience with the 7.9mm round, many military-use loadings were developed; tracer, armor piercing, incendiary, aerial spotting, explosive, ball, grenade launching, signal, blank, tropical, tool cartridges, multiple bullet and on and on are some of the varieties. All these and more were either made or contracted   by each of the several nations  that adopted the round as their service cartridge. It is probable that there are more varieties of the 7.9x57mm round than any other cartridge ever made. At least 40 countries have loaded the ammunition!

Being a successful military round meant automatic success in the civilian market as a hunting cartridge. In Germany, Mauser offered its commercial sporters in the 7.9mm chambering. Countless small gun builders produced Mauser-actioned hunting rifles for export to Asia, Africa and South America. Few, however, were seen in the U.S. or Canada.

It is safe to say, every producer of sporting ammunition in the world has made 7.9mm at some time. Varieties are almost as endless as military rounds.

Close to home, CIL of Canada for many years loaded a 170-grain softpoint at 2,530 fps muzzle velocity. This yielded 2,415 foot-pounds (ft-lbs) of energy. The slug had a rather blunt point and was given a streamlined profile in the 1950s. Velocity was also upped to 2,570 fps.

In America, Federal, Remington and Winchester all offer only one loading today. It’s a 170-grain  softpoint at 2,360 fps from the muzzle of a 24-inch barrel. Worry of the rounds being fired in the old Model 88 Commission Rifle is probably the reason. The 7.9x57mm is far better than this.

European ammunition is a different story. RWS, DWM and Norma turn up the speed significantly. Bullets weighing 185 to 200 grains are available at published velocities over 2,600 fps. Bullets of 170 grains can be driven at least 2,700 fps; 150 grainers can reach 3,000 in some rifles. This equals or exceeds the .308 Winchester.

Handloaders too can make the 7.9mm shine. There is an adequate variety of high-quality hunting bullets available, and empty cases are not hard to find. Often the above velocities can be safely exceeded in individual rifles due to the long throats seen in many 7.9mm chambers. If ever a round existed that careful handloaders can really make perform, this old cartridge is it. A little field use will leave experienced riflemen wondering why many of the newer small cartridges were ever created.

Big Game Rifle
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