I have not deployed for combat, but I have never experienced a stoppage with any M-16 family weapon using live ammo. The only problems I have had were with blanks, and even then I usually found that if I switched out magazines, to find the newest-looking one with the best feed lips and mag release hole, it worked a lot better.
I just had a discussion at WLC with a guy who insisted that we should switch to a rifle with a piston system, because it would be more reliable. He had never fired one, but wouldn't be convinced otherwise. So I started, I told about when I had fired 500 straight rounds from a Bushmaster M-4 without a single stoppage, and went all around the room, asking guys who were various flavors of infantry, cavalry, and other combat MOSs, (Including a former Marine who had been deployed,) not one of them had ever had a stoppage with an M-16. Keep it reasonably clean, shut the dust cover, it will do what you need it to, when you need it to do it.