Tuning a mis-timed lock

[rich pierce]

A friend gave me a repro Barnett trade gun flintlock that wouldn’t work for him. Requires a very short flint then won’t turn over. Diagnosis is the cock is mis-timed relative to the half cock notch. Time to fix that. It had been previously re-timed by drilling out the square hole in the cock then threading in a bolt and silver soldering, then cutting the square. I decided to use a tapered square patch. I’ll braze it in place then hopefully get it timed right. Will post progress. Think I need about 5 degrees more setback.

[shifty]

  looking good so far.

[rich pierce]

Got the plug fitted and brazed in place. Not perfect flow but it’s not going anywhere. To “time it” I inked the inside surface of the cock around the tumbler axle hole.

Then  screwed the cock down onto the square tumbler axle shank. Then with the lock on half cock I put a flint in the jaws and rotated the cock on the tumbler axle till I had a bit more gap between the flint edge and the frizzen. I tightened the cock screw down tight.

Then I used a triangular needle file to slip in between the lock plate and tumbler. I used that to mark the tumbler axle square on the inside of the cock. After filing and trying it fit good and tight. Fun stuff. Now it’s timed better and I can use a regular length flint. I gained about 1/8”.









These last 2 photos above are in backwards order. Best I can do from a phone.
I often see folks posting they want to make locks from scratch and just want some plans. I find that very small changes in dimensions and angles make a lock fail or succeed. Still learning.

[Clint]

I made two pistol locks a few years ago and one of them had this problem. I had cut the tumbler notches to match a pattern prematurely and the flint kept the frizzen from closing at half cock. I considered doing just what you are doing to the barnett but the flint cock was too small. I annealed the sear and filed the nose to accept a small piece of steel about .20 " longer than the original sear nose and brazed it. I ground the nose back until the flint cock stood up straight and was lucky that I didn't have to move the full cock notch.
Clint

[rich pierce]

Cool fix, Clint. Would have been less work, for sure. Thank for that “tip”!