Aren't those a BIG bag of worms?

A pistol? Nope, no bag of worms at all as long as you don't put a
shoulder stock on them. If you're building your own custom short pistol
buffer that makes it pretty clear a standard shoulder stock isn't going
on it. No vertical grips on the front either, so ideally use a style of
handguard that doesn't lend itself to that, like a basic round one vs. a
quad rail.

Not a bag of worms but certainly a flame thrower.

Careful not to cross the alphabet boys here. You can't convert a rifle
into a pistol. You have to start with areceiver that was never on a
rifle. Don't know if the rule is activiely enforced, but it is there.

FWIW, I think the AK makes a better pistol, no large buffer tube
sticking back. real cheap build too.

Karl