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Lock slipping

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pdt1793db

32 Cal.
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So a while ago I had a Pecatonica Tennessee Mountain Rifle kit built for me with a Siler lock. Took it out shot approximately three rounds. Load the fourth, try to bring it to full cock, and bang it goes off. Really glad I had it pointed down range at the time. Anyway, thought it was dirt or something, clean the gun, and adjust the set trigger screw. Lock still slips when placing slight forward pressure on the hammer. It does this when I take the lock out of the rifle also. So my question is. What do I do about this? Do I need to strip the locks internal parts and start over?
 
First check to make sure that there is no interference between the sear and the stock, the bottom of the hole for the sear arm especially. This can keep the sear from fully engaging.
 
As what Pete said, as well as the trigger slot. Make sure everything moves freely that actually should. This time of year wood will be as swollen as it's going to be and some binding is likely happening. Certainly wood is more so now than towards the end of winter.
 
I'm pretty sure the stock is not the issue but I'll check it when I get home. This morning I removed the lock, brought it to half cock, pressed forward on the hammer and no issues. I then brought it to full cock, pressed forward on the hammer and it went off. So regardless of the stock its slipping in full cock without the sear being engaged.
 
The sear and / or the tumbler full cock notch are not square. Even with minimal sear spring pressure the lock should stay at full cock if the surfaces are properly shaped. You state that the lock is clean but recheck these points then if necessary stone the engaging surfaces to make them sharp and square and at the correct angles. Also make sure the sear screw isn’t over tightened. If in doubt have this done by a smith.
 
With the lock out of the stock, move the sear by pressing up on its arm. It should move easily with the only resistance coming from the sear spring.
With the sear moved so that it is not pressing against the body of the tumbler, closely look at the edge of the sear that engages the tumbler notches. It should be sharp and have no chips in it.

With the lock set to full cock you should be able to clearly see the sear engaging the tumbler full cock notch.
Closely examine the edge where the full cock notch meets the outer surface of the tumbler. It should be a sharp edge with no chips.

If it is at all rounded off the lock will need a new tumbler. (I don't recommend that people without the proper training should try to reshape or sharpen the full cock notch.)

Wh
 
Great advise Zonie. I'll check it out and let you all know what I find. Might post some pics. Thanks again.
 
Before doing anything to the lock I would call Jim Chambers and tell him what's going on. That lock should still be in warranty. I'd rather have a lock fixed by a Master than one just "Fixed" out of luck.
 
First....If this is a Chambers lock, send it to Jim.
I had a Chambers large Siler that was behaving a lot like you describe. In that case...Turned out the fly was too short. The nose of the fly had been polished by the rifle builder with the idea that it would function better (I suppose). Got it just a hair too short. Jim took a quick look, tossed me a new fly... fixed it right up.
 
Sorry, I can’t. I’m not sufficiently well trained to provide that. Just passing along personal experience, not my opinion, but that of an expert in the field which might be helpful to someone experiencing a similar problem.
 
Ahh, please explain to me how a too short fly has anything to do with sear engagement at full cock.

I agree with Wick, but perhaps Don meant a fly that was too LONG and that can interfere with the sear engaging the Half Cock notch correctly, but would not affect the engagement of the full cock notch?

Gus
 
If the lock IS good outside the stock, then it is probable the sear leg is hitting the wood in the stock and not allowing the Sear to go high enough into the full cock notch, or the set trigger/s are inletted too close to the Sear or even though very rare, the bottom of the trigger might be hitting the trigger guard.

Gus
 
It does this when I take the lock out of the rifle also. So my question is. What do I do about this?

Just my 2 cents....
My hunting buddy's fowler started to do that, even OUT of the stock as yours does. Took a look...
Broken sear tip.
The sear was too brittle, and his young son had shouldered the fowler, with the lock at half cock and had pulled the trigger, thinking it was at full cock. He wasn't supposed to be handling the gun..., oh well. He put it back and it appeared to be working right.
My buddy didn't discover the problem until hunting season last year.

With the sear tip broken the remaining parts function..., but where the sear interfaces with the tumbler, it barely catches the edge of the half-cock notch, and doesn't fully go into the slot for half-cock position. So it acts as though it's at a full-cock position on the tumbler, and a little pressure causes what little friction is holding the tumbler in place, to give...., voila.... the cock falls from the half-cock position. It goes off half-cocked.

As mentioned send it back to Mr. Chambers.

LD
 
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