Failure to fire after trigger rebuild

Hi All

I just rebuilt the trigger with the MCarbo trigger rebuild kit and after two or three rounds, I got a failure to fire. I racked it and checked, the primer was dented, then it ran a couple more shots fine, then it failed again in the same way. Racked it again and got a couple more good shots, then another failure to fire. I didn’t make any changes to the hammer or bolt other than to clean them up while I had the rifle apart. Any suggestions as to what I did wrong?



Have you tried different ammo? If the primer was dented but didn’t fire, could it be the ammo? Or was it a very light primer strike?


Welcome aboard @CaptainHindsight style points for the SN. Possibly the firing pin and channel are fouled. Clean and re-assemble without any oil.


Welcome to the firm @CaptainHindsight .
what ammo and magazines are you using?


Hey All

Thanks for the prompt replies! Here is what I have so far:

  • I was using Winchester white box, tried S&B ammo with the same results. For magazines, I was using the factory mag; using a Glock OEM mag has the same issue.
  • @Festus I field-stripped it, cleaned and re-oiled the bolt and made sure that everything was running smooth. Then I reread your post. I’ll pull it apart again and dry everything out. Is it possible/feasible to take apart the bolt to clean out the channel where the hammer lives?
  • The primers on both the spent and FTF rounds were dented, though it looked like it could have been light.

I did notice something odd: the spent casings on the rounds that went were burned pretty good on one side. I don’t know if that is normal or not but I have never noticed that before.



the same ammo that didn’t fire, have you refired the round in a different gun?


OK, I think I have it figured out. Here is what I did:

  1. Took the rifle completely apart
  2. Cleaned, dried and put a very light coat of oil on everything
  3. Reapplied small amount of PTFE to connection points on sear and hammer
  4. Re-watched both videos and CAREFULLY reassembled the rifle

Took it for a test drive and it ran both brands of ammo just fine. My best guess as to what went wrong is one of the internal parts was just a little off/misaligned, most likely the hammer; it was off just enough to function but was binding up and not striking with enough force. BWT the MCarbo performance trigger kit makes a big difference; it is basically a new rifle.

Thanks all for your help!


Every now and then, I drop rifle bolts into a small ultrasonic cleaner. A couple of times a year at most (depending on how many rounds have been thru the rifle), I will take it completely down and look at the firing pin. Over time, you can get funk in that firing pin channel. Carbon and it’s not uncommon that some oil or melted grease finds its way in there. A lot of people over-lubricate their guns.

After I’ve cleaned everything, I toss the spring and pin in Ballistol for a few minutes them wipe it all off before reassembling.