Morons.
Among other things, the fact that they have differening definitions for "muzzle brake" and "muzzle compensator," as well as the fact that in defining a barrel shroud they don't define what "substantially" means, strongly suggests that this bill was assembled by know-nothings.
Does a WW2 surplus M1 carbine have a shroud which substantially encases the barrel? How about a Mauser 98?