Gun Control Reform Activism

Muzzle energy wouldn't be ideal, without going into unnecessary "technical detail" (everything in moderation), these AR "pistols" only deliver about half the energy of a .44 Magnum, but the former will penetrate soft body armor, while the latter is the specified standard to be stopped.

There's many other factors at play besides ME in terms of a round defeating soft armor; I'd advocate for simply lumping any repeating-action firearm that uses a cartridge designed for a rifle, with a barrel less than 16", to be classed as an SBR regardless of presence/absence of a stock. It seems to me it would rather tidily wrap up this whole mess without getting into murky gray areas (ME isn't a fixed number, after all).