>>64356526
Here’s a mock-up of a 30 carbine case necked to 224. I plugged the cartridge specs into an internal ballistics computer, and at 80kpsi, it predicts a muzzle energy of roughly 1250ft*lbs. bullet is 5 calibers long, i7 should be between 0.8-0.85. And the point of the 30 carbine case is 1) reduced case weight and 2) 80 round desert-tech style quads stacks no longer than the surefires.

5.56 FABRL was a stroke of genius, it’s a shame that cartridge went nowhere. If you haven’t (you probably have), check out the 4.85x49mm. It’s like the one good firearms-related thing the Brits have come up with. That, with an even shorter case and longer bullet, at 80kpsi, would also make for an excellent cartridge.