12 Nov 19
A Tale of Two Cartridges:
When WWI ended in November of 1918, most nations had come to the conclusion that bolt-action military rifles were now obsolete, and work on autoloading systems continued in earnest!
Two autoloading military rifles that actually saw some production and issuance during the War, were the French RSC and the Mexican Mondragon (named after General Manuel Mondragon)
The Mondragon, chambered for 7×57 Mauser, was a long-stroke, gas-piston, rotating-bolt, autoloading rifle, manufactured for the Mexican government by SIG in Switzerland, starting in 1908. It was probably the first semi-automatic rifles actually issued to troops and subsequently involved in active fighting. However, the Mondragon quickly developed a poor reputation, both in Mexico and in Europe, where many copies ultimately ended-up.
The RSC was also a long-stroke, rotating bolt, gas-gun, and saw service in Europe at the very end of the War. It was chambered for the rimmed 8mm Lebel cartridge and also did not enjoy a stellar reputation, largely due to the fact that rimmed cartridges (designed for tube-magazines) do not work well in box magazines.
As the War ended, the French were anxious to create a successor to the 8mm Lebel Cartridge, as the Lebel’s rim and heavy taper made it mostly unusable in box magazines, as noted above.
Their answer was the straight-walled, rimless 7.5×58 French cartridge, similar ballistically to the American (Winchester) 308 (7.62×51), that was to be later adopted (1954) by all of NATO, at the insistence of the USA.
The update was to be immediate and global. The new French LMG, the Chatelleralut, and the subsequent new French Bolt-gun, the MAS 36, were both slated to be chambered for the new round.
Serviceable copies of older weapons, like the bolt-action Berthier, were also scheduled to be to be re-chambered for the new round.
The French, along with the British, Germans, Russians, and Americans were also feverishly at work on a practical autoloading infantry rifle, as noted above.
But, only the Americans actually got it done prior to the outbreak of WWII (May of 1941), with the Garand, and later the M1 Carbine. Other nations mentioned put their versions into production and issuance only in the late 1940s and 1950s.
Back in France, captured German weapons, heavily used by French colonial forces after WWI, were mostly chambered for 8mm Mauser (7.92×57).
The two cartridges (8mm Mauser and the new 7.5×58 French) were so similar in external appearance, that one was constantly mistaken for the other.
When a 7.5×58 round was mistakenly chambered in an 8mm weapon, it would fire, but most of the gas would blow past the undersize bullet. The bullet would be projected out the end of the muzzle, but at an inadequate velocity, usually falling to the ground a few meters downrange. It wouldn’t hurt the weapon, but the resulting shot would, of course, be ineffective, and the weapon’s action would not have cycled.
Conversely, when an 8mm Mouser round was mistakenly chambered in a 7.5×58 weapon, it usually resulted in catastrophic bursting of the barrel, which destroyed the weapon and sometimes injured the shooter.
The solution the French came-up with (1929) was to abandon the 7.5×58 French cartridge and replace it with the new 7.5×54.
They simply shortened the cartridge by 4mm.
Now, an 8mm Mauser cartridge, mistakenly finding its way into a Chatelleralut LMG, or a MAS 36, will be too long and therefore the bolt will not close, nor will the weapon fire.
Thus, this otherwise excellent cartridge (7.5×58, French) enjoyed only a short existence (1924-1929).
Today, the French 7.5×54 cartridge enjoys a small following, and several ammunition manufacturers produce it in modest quantities.
The long-obsolete 7.5×58 cartridge is confined to museums!
Curiously, we have a similar dilemma in our age when 5.56×45 (223) become mistakenly mixed-together with 7.62×35 (300BLK), with similar results!
However, it looks as if neither the 5.56×45, nor the 300BLK, have much of a future, as least as military calibers.
The 6.8SPC (6.8×43) has now emerged as the “wave of the future.”
Time will tell!