I have a post (1994) ban Colt HBAR 1in7 twist. My rifle does not have the flash suppressor or the bayonet lug. None of the Colt HBARs post-ban have the flash suppressor or the bayonet lug.
Personally, the flash suppressor and the bayonet lug don't do a thing for me. It's not like I'm going to be fixing bayonets and charging up a hill anytime soon. Otherwise this rifle shoots the Sierra 77gr HPBT into 1/2 MOA. That's what really counts for me.