“What the world really needs is a .30-caliber pistol cartridge that, while more powerful that .32 ACP, is not so powerful that it requires a locked breech…” said no one ever. Not even me, and it’s my idea. It’s not even a new idea; the French had a .32 service cartridge that was rather similar. Hmm… better run it through the Wildcatter’s Checklist:
*Does it duplicate the performance of an existing cartridge? Check!
*Does it answer a question no one is asking? Check!
*Is it a pain in the butt to make? Check!
*Is it of dubious utility? Check!
*Will it be fun? Check!
Oh look, a perfect score! I guess we’d better get on with it then. Ladies and Gentlemen, I give you… drumroll please… the 7.8x19mm Auto!
A couple years back someone gave me some .30 carbine brass, and it was inevitable that I’d find something to do with it sooner or later. Shortened and resized is turned out to be a pretty perfect donor-cartridge for the 7.8x19mm.
Umm… why 7.8mm? Well, because it turns out the .308 bullets are actually 7.82mm in diameter, not 7.62mm. No, I don’t get it either, but that’s the way it is. OK, why 19mm long? Because for the methods I had on-hand it was easy for me to shorten them to that length. I was shooting for 20mm and got 19 and said, “good enough.”
Of course I’ll need some way to test it, and as it happens I have a Maadi Helwan pistol converted to a .380 ACP straight-blowback already, and guess what new cartridge fits in a 9mm Helwan magazine?
OK, the 7.8 fits in the magazine, and it feeds, extracts and ejects from the .380-chambered barrel. So if I bore out the barrel, line it with a .308 barrel liner and cut the chamber for the new cartridge it just might work…
The goal here is to see if I can drive a 100gr. bullet to 1000fps. and still operate safely as a straight-blowback. This will yield 222 ft./lbs of energy at the muzzle, and the bullet’s high sectional density ought to give it excellent penetration, hopefully even with an expanding bullet.
As it happens I have a short section of .308 barrel and some Speer 100gr. .308 Plinkers. I also have a .308 resizing die I use to resize .312-caliber bullets to .308 for use in my Mauser C96 broomhandle. This is a totally doable thing…
Of course the question of whether one should do a thing just because one can comes up… to which I say, ‘Why the hell not?’ It’ll be fun, and if it doesn’t work out I can always get another barrel for the Helwan and turn it back into a .380, or even get one of the new locking blocks from that fellow in Europe and restore it to 9mm.
So is this new cartridge going to set the world on fire? Uh, no. The world manifestly does not need this cartridge. I expect I will go to my grave as the only person to own a firearm chambered for it, in fact. But it will be fun, and that’s really the whole point.
Naturally whatever happens I’ll keep you posted.
Michael Tinker Pearce, 23 January 2021