Bushmaster xm15 problem

[Cornmilitia]

I Have a bushmaster xm15 that is failing to fire, when shooting ammo of all types it strikes the primer but about one out of every ten to fifteen rounds it doesn't go bang. If i try firing the same round again it will go on the second or third strike and sometimes not at all. My buddies rock river and both my dads stags will shoot em even after i try repeatedly so i know the rounds are good, could i be in need of a new firing pin or the whole bolt assembly? I'm looking for the cheapest route first if possible and any input would be greatly appreciated.

 

[mvician]

First tear the bolt carrier group down and give it a good cleaning.
How old is it? How many rounds have you shot?

 

[sloughfoot]

After cleaning the BCG like mvician says, check the hammer spring. It can be installed backwards.

Also, since every AR owner should have a couple of extra firing pins, compare one of your spares to the one in the gun.

 

[SSGSAD]

Or, MAYBE you can swap firing pins with another weapon, and try that .....