Ar15 not firing.

[acmax95]

I recently assembled a new AR15. On the first range trip i had a failure to fire. I could not get any rounds to fire through the gun. I could load a mag and charge the rifle but when i pulled the trigger i just got a "click.". I could pull the charging handle and eject the unfired round and the next round woupd chamber. I tracked the issue to the BCG.

I swapped BCGs and the rifle functioned fine. Any ideas what i need to be checking on the faulty BCG?

 

[ClickClickD'oh]

Check for free travel of the firing pin. If assemble wrong, the firing pin retaining pin may keep the firing pin from going forward.

 

[rcmodel]

Did you get any primer dent at all when it didn't fire?

I'd start by swapping firing pins with the one that works.

If that don't work, swap the complete bolts in the carriers and try that.

If that don't work, compare the two carriers and see if there is any noticeable differences in the hammer clearance cuts where the firing pin head sticks out.

rc

 

[Bexar]

Did you use the same bolt in both carriers?

http://www.youtube.com/watch?v=4X_D6UH3dLM

 

[carbine85]

To accurately answer the question we need to see the primers. It's all speculative without a good description or pictures of the primers. Compare primers from a fired and unfired.

 

[barnbwt]

Always never forget the camming slot; I've recently heard of at least two issues involving bolt binding or misfire that I suspect are due to the bolt not clocking into position properly, and the camming slot would be a likely culprit for causing that. It's probably the most tolerance-critical element of the whole bolt carrier assy.

TCB

 

[acmax95]

Turns out it was firing pin. Replaced it and was good to go.