[BattleRifleG3]

Pistol barrel must be under 15" or so and have never had a buttstock attached. Now it's legal to attach a buttstock and a long barrel to a pistol and make it a rifle, and then change it back, but not to take a rifle and make it a pistol. Then you'd just be making an SBR. So a pistol must have rifled barrel, grip angled to bore, barrel under 15", and never have a buttstock.

Then comes the stinky ban. It says if you have a detachable magazine, you may only have one of 5 features:
1. Mag outside grip
2. forend (not foregrip, that would make it an AOW)
3. threaded muzzle
4. weight over 50oz
5. Semi version of full auto gun (I think this may have been struck down in court)

So since a 308 caliber FAL definitely has a mag outside the grip, will be a heavy sonovagun, really needs a forend to be held properly, may be considered a semi version of an auto gun, and heck, if you have all those features, might as well have a threaded barrel muzzle too, the only way to legally have a pistol in this configuration is to make the magazine fixed. Such AR pistols must be opened to load, AK pistols often have a back loading drum welded in place while some drill a hole in the back of a normal mag and pull down the follower to load each shot, but FALs have the advantage of being able to load from stripper clips. No 223 that I know of can feed from strippers, and the only 7.62x39mm that I know of is the SKS, for which I have never heard of a virgin (never had a buttstock) receiver being available.

So really the FAL is the only easily buildable rifle with plentiful virgin receivers that can be loaded from strippers.