Thompson Center Hammer Only Fall to Half Cock

[Von Hayek]

I have been looking to bring my father's Thompson Center Hawken flintlock back into service. Unfortunately, once out of every six trigger pulls or so, the hammer falls to only half-cocked. Is there a common problem I can look for that would cause this?

[Daryl]

Take the lock out and check the fly. Sounds as if it is not working correctly. It could be it's gummy(dried oil or grease) in there or it's broken.
Work the lock several times and observe it's action. I would suggest you don't dry-fire it. You should be able to see if it is working correctly.
Dunks in solvent - Varsol should work & will do to clean out old oil or grease.

[Von Hayek]

Thanks. I'll take it off the gun and have a peak. Does dry firing hurt flint locks? If I have a flint in the hammer, I was thinking it would be fine.

[Daryl]

Firing it against the closed frizzen is fine, out of the gun or in. You could also put a piece of flint shaped wood in the cock's jaws to save the flint.

[TDM]

Thanks. I'll take it off the gun and have a peak. Does dry firing hurt flint locks? If I have a flint in the hammer, I was thinking it would be fine.

I recommend using a flint sized piece of wood for dry firing for two reasons, eliminates wearing out a good flint and reduces wear on your frizzen face. The TC frizzens don't have a lot of hardened surface to spare.

[D. Taylor Sapergia]

Dry firing it and having it stop in half cock will eventually damage the tip of the sear and/or the tumbler.  Fix the issue first.

[Von Hayek]

Thanks gents. I haven't had the lock out yet, but I will report back when I do. All good advice.

[Von Hayek]

Well, I fixed it. It was an easy one and I learned some terminology in the process. The two bolts securing the bridle were extremely loose, allowing the fly to wedge itself between the loose bridle and the sear. Tightening those two bolts fixed the issue--I wish all my problems in life were so easy to fix!

[Dphariss]

Now you need to check the sear nose and 1/2 cock notch for damage. Bending of cracks/chips.