The introduction of the .30 Super Carry highlighted that, whatever you think of the cartridge, it’s a weird time to introduce a new caliber. Material shortages, particularly primers, has caused a bit of an outcry over wasting materials that could have been used for cartridges people already like.

I am not a manufacturer, and my use of primers will not affect the market for popular calibers, so I feel free to do as I please. OK, I probably would anyway; they’re my primers after all. I was looking at a cartridge that flopped and thought, “Hmmm… I can expand on that failure with another cartridge no one will want!”

7mm Penna…

…also sometimes called 7 x 23mm. This cartridge is based on a shortened 5.7×28 cartridge with a .277″ bullet. Of course it’s not a 7mm, it’s a 6.8mm. Everyone lies about their caliber. Designed by Leonardo Penna as a lightweight, low-recoiling cartridge for high-capacity pistols. With a special pointed lightweight brass projectile travelling at around 1600 fps the round would have some ability to pierce soft body armor and perhaps have enhanced effectiveness, useful for law enforcement applications. The 49gr projectile would achieve 279 ft./lbs of energy. Another option was a 69gr projectile propelled top 1330 fps., producing 271 ft./lbs. The cartridge was firmly in the range of .32 H&R Magnum in power. Not a world-beater, but possibly useful.

My introduction to this cartridge came 10-11 years ago at SHOT Show, where I examined the pistol pictured above and spoke to a nice Italian gentleman whose name I did not catch. It’s a very flat, compact pistol and I was intrigued, but I didn’t dive too deep because there was so much to see at the show and my time was limited.

Fiocchi developed a version of the cartridge they called 7x23mm (‘version’ meaning they re-named it) with an eye on the competition market, specifically IPSC, where they felt its low recoil and high capacity would be seen as an asset. STI chambered some of their 1911-based competition pistols for this round, but it never caught on and was dropped from their line. The cartridge has since languished in the status of being a historical footnote, just one of many mildly interesting side-bars in the line of firearms progress.

I have a cunning plan!

I have sometimes thought there might be room in the world for a .25 ACP Super, something with little more size but significantly more speed. I’m probably wrong. It was these thoughts, in part, that led me to develop .251 TCR, a straight-walled rimmed .25 caliber pistol cartridge that exceeded .22 Magnum in power, but was centerfire and reloadable.

I was handicapped in developing a semi-auto cartridge by the lack of a parent case and the fact that converting a semi-auto pistol to another caliber is hard when you cannot simply buy a new barrel in the correct caliber. I’ve since done a semi-auto cartridge conversion and it’s less daunting to me now. Anyway musing on the 7mm Penna got me thinking and I was unsupervised at the time so I thought, ‘What if I shortened 5.7x28mm to 19mm and loaded it to 150-200 ft./lbs?’ The answer of course is that no one will know what it’s for or why I bothered, but it sounded like fun…

5.7 x 28mm brass is not hard to come by, but 6.8 mm bullets are all made for rifles and are too long and heavy for my cartridge. What to do? Contact my buddy Steve, who takes a perverse delight in making bullet-molds for obsolete cartridges, figuring out how to make new brass for cartridges long out of production and generally messing about with fun and useful stuff in the world of reloading. At some point in the relatively near future he’ll be giving me a call… We’re looking at three cavities that will produce bullets between 50 and 70 grains and we’ll see what works best.

Gee, That’s Swell. But What’s it For?

The target is to drive a 70gr. hard-cast lead bullet to 1100 fps and yielding 188 ft./lbs of energy, about average power for a .380 ACP. Penetration should be excellent; the bullets will have a high sectional density and enough energy.

Honestly I thought this was a kind of silly project, but .380 power with a few extra rounds in the magazine? That might actually be useful. Or picture it in a sub-sub-compact that is very, very flat. Hmm…

Let’s get real, though. Some weirdos like me will be interested, but commercially? Not going to happen. Still, it will be fun and interesting. I’ll be using my Maadi Helwan again, re-lined and re-chambered for the new cartridge. I’ll be set up as a straight-blowback again, and based on my work with my 7.8x19mm it ought to work just fine with some adjustments. I’ll have to modify the magazine and follower, but it’s nothing I haven’t done before.

So, off on another wild goose-chase. I’ll need a short section of 6.8mm barrel, some 5.7mm reloading dies and 5.7x28mm brass. I might have to enlist the aid of my welding0buddy Ernie again, but perhaps not… I have another cunning plan. Naturally I’ll keep you posted.

Stay Safe and take care,

Michael Tinker Pearce, 6 Febuary 2022

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