if you dont reload your going to not be happy at all with the blackout. hard to find ammo and when you do its more expensive than 223/556
an A3 means no M4 cut ramps. A4 has M4 ramps. if you use a A3 the barrel ramp cut doesnt matter but if your reciever is A4 with the cuts you can only use barrels that have the extensions cut with the M4 ramps. both have rails on top.
"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