I'm late to the party but IMHO, look around and spend the extra on a Colt SP1 20" rifle.
It'll be the real deal Colt in the config you want. Early SP1s get the 3-prong, later SP1s get the birdcage. I think the last of the SP1s had the FWD Assist?
I have one and had been looking at asking prices to get a sense of market value for my gun; the SP1s are not that crazy as everyone wants that Call of Duty M4rgery look.
A close and cheaper alternative are the Century subcontracted "C15" - mostly Colt M16A1 parts but with a new lower and barrel. If I didn't have an SP1 already and badly wanted one, I'd consider it as a budget-tolerable alternative.
In a victim nation, a classroom full of dead children is morally superior to a teacher holding a smoking gun knowing she just protected her students.