When firing rapidly, or bump firing, some times my Olympic Arms ar will load a round into the chamber but when you pull the trigger nothing happens. I have to pull the bolt back and load a new round and it is fine. I can load the round up that didnt fire and it will fire fine. Also it usually leaves the last round in the mag and set the bolt back. I figured this is just my crappy mags but I am not sure. It has done this with both Wolf and winchester white box. Sorry if something similar has been covered, but I couldnt get the search to return any thing useful for me.

The first problem is hammer follow.  You may need to replace parts of your trigger group.

The second problem is likely to be mag related.

If it ONLY happens during rapid/Bumpfire  (and not slow aimed fire),

then it's just your trigger finger technique.

Quoted: the hammer is following most likely due to minimal disconnector engagement, we've covered it here in detail a couple times this week. if the bolt catch is popping up mid mag then your bolt catch spring may be too light or its hole too deep.

Could you point me to those threads. Still not having luck with the search.  This rifle as had maybe 1500 - 2000 rounds through it by the way.

EDIT:the round that didnt fire have a slight mark from the firing pin hitting them.

Quoted: If it ONLY happens during rapid/Bumpfire  (and not slow aimed fire), then it's just your trigger finger technique.

BINGO - this is a problem with bump firing... you are tripping the trigger before the bolt is fully locked in place, and so the hammer falling prematurely. The dent on the primer is normal, and nothing to do with this problem. If you must bump fire, work on your technique. Do not go looking for a problem with your rifle - chances are its 100%.

Quoted: Quoted: If it ONLY happens during rapid/Bumpfire  (and not slow aimed fire), then it's just your trigger finger technique. hr BINGO - this is a problem with bump firing... you are tripping the trigger before the bolt is fully locked in place, and so the hammer falling prematurely. The dent on the primer is normal, and nothing to do with this problem. If you must bump fire, work on your technique. Do not go looking for a problem with your rifle - chances are its 100%.

Alright, Thank you, I just wanted to make sure that something wasnt wrong. I just had to urge to try the bump firing out. I usually am a lot more convservitive with my ammo ;)

Bolt carrier bounce. As the hammer starts to fall the carrier is bouncing back preventing the hammer from hitting the firing pin. Thus the reason the heavier buffer cured your problem.

Quoted: Quoted: the hammer is following most likely due to minimal disconnector engagement, we've covered it here in detail a couple times this week. if the bolt catch is popping up mid mag then your bolt catch spring may be too light or its hole too deep. Could you point me to those threads. Still not having luck with the search.

ar15.com/forums/topic.html?b=3&f=66&t=262667