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The Small Arms Thread, Part 8: 2018; ICSR to be replaced by US Army with interim 15mm Revolver Cannon.


Khand-e

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New ammunition idea. Basically, it's a lengthened 9mm case necked down to .30 cal, but what's important is that the barrel twist rate is adjusted to work with both long, heavy .30 cal subsonic bullets and sabots firing .22 cal bullets at high velocity. In theory, you should be able to switch from a subsonic round firing a 240gr Sierra MK at about 1,050 ft/s, to a supersonic saboted round firing a 37gr .22 cal long-ogive plastic-cored bullet at almost 3,300 ft/s. Being .30 cal and able to stabilize some pretty long bullets should open the round up to a bunch of specialty loads, too, including supersonic lightweight full-bore .30 cal projectiles. The round is based off a 10mm diameter case head instead of the 9.6mm diameter case head to hopefully solve the .300 Blackout's problem where it can with enough effort be chambered in a 5.56mm rifle and cause a kaboom. The shorter case length should improve pressure levels with subsonic bullets and improve functioning consistency between subsonic and supersonic ammo vs. the .300 Blackout. Somewhat shorter ammo than 5.56mm (49.2mm OAL vs. 57.4mm) would require new rifles and magazines, but at least those rifles and mags would be smaller and lighter than existing kit. Supersonic saboted 37gr ammunition would also be approximately three-quarters the weight of 5.56mm, as well, with a steel case.

Lqo22qd.jpg

 

Downsides would include potential accuracy problems with the saboted ammunition (given the intended use, that may not be a big deal), limited available muzzle energy (~1200 J from a 10" barrel compared to .300 Blackout's ~1575J from the same), and short range with basically all loads (even the supersonic .22 cal saboted loads would lost velocity pretty quickly, being ballistically similar to M193). 

 

It would, however, like the .300 Blackout, be 50-state hunting legal.

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If you were willing to use a brass case, you could start with 9mm Winchester Magnum cases.

 

New ammunition idea. Basically, it's a lengthened 9mm case necked down to .30 cal, but what's important is that the barrel twist rate is adjusted to work with both long, heavy .30 cal subsonic bullets and sabots firing .22 cal bullets at high velocity. In theory, you should be able to switch from a subsonic round firing a 240gr Sierra MK at about 1,050 ft/s, to a supersonic saboted round firing a 37gr .22 cal long-ogive plastic-cored bullet at almost 3,300 ft/s. Being .30 cal and able to stabilize some pretty long bullets should open the round up to a bunch of specialty loads, too, including supersonic lightweight full-bore .30 cal projectiles. The round is based off a 10mm diameter case head instead of the 9.6mm diameter case head to hopefully solve the .300 Blackout's problem where it can with enough effort be chambered in a 5.56mm rifle and cause a kaboom. The shorter case length should improve pressure levels with subsonic bullets and improve functioning consistency between subsonic and supersonic ammo vs. the .300 Blackout. Somewhat shorter ammo than 5.56mm (49.2mm OAL vs. 57.4mm) would require new rifles and magazines, but at least those rifles and mags would be smaller and lighter than existing kit. Supersonic saboted 37gr ammunition would also be approximately three-quarters the weight of 5.56mm, as well, with a steel case.

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Oh yes, I think the Baryshev is basically an open bolt API lever-delayed blowback constant recoil design. Supposedly, it isn't very reliable, and certainly being open bolt single-shot accuracy leaves a lot to be desired.

It does illustrate, however, just how little actual recoil comes from the 5.45 cartridge (most recoil comes from the elastic collision as the bolt group smacks into the back of the receiver).

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For the record on the Vz. 26, I think Ian was being a little unfair to it. It's not the most inspiring SMG to shoot, but I think it was very well designed for its intended purpose. I mentioned to him at the time that point shooting was at that point still widely taught, so the weird stock/foregrip makes sense in that context (if you are carrying the gun by the sling with the stock folded and you need to deploy it quickly, you just pull it to your hip gripping the butt/foregrip and shoot, without worrying about deploying the stock).

Now, it's very strange to modern users, but as always context matters.

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