>>8770140You could maybe squeeze 1500fps with a 180gr gold dot from a 10" barrel with 10mm
.357 rimless mag feeds from standard AR mags and will easily reach 1700fps from a 10" barrel with a 180gr bullet. Given its higher BC, SD and velocity its a much better cartridge. But you exclusively have to load your own ammo for it.
With 5.56 or 7.62x39 the best performing short barrel loads are expanding TSX. They don't have the best expansion around but are still nothing to scoff at. Though given the high pressures of these cartridges and the effects they have on short gas systems a lower pressure cartridge like .357 rimless mag is much more desirable especially so considering its greater potential for expansion
pic related
.308 and .277 TSX bullets recovered after being fired into gel. A heavy .357 HP would put these to shame