eitehr way if you have a fixed front sight base you give up the most solid durable front sight there is and possibly a bayonet lug. you get rail space if you need it and prolly gain some weight or lose some weight depending on whats there now compaired to what your installing. if you have a fixed fsb you will need a low profile gas block as well.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent