Lock will go off half cocked.. baffled???

[Hisownself]

I've spent the past couple weeks reading about locks (flinter) and doing some work on mine. It's a Davis and works really well, but I can cause the hammer to fall if I pull on the trigger hard enough(single, no set). Hammer won't fall when out of the stock. So....

There was some rubbing and binding in the stock. I relieved everything and now there doesn't appear to be any rubbing or binding. But still, the hammer will go off half cocked.

If it's out of the stock half cocked no amount of force I put on the sear will cause it to drop. But if I gently slide it into the stock and hold with my thumb and pull the trigger, it drops.

I cannot see any wood what-so-over getting in the way. I just don't get it!! Any ideas????
Regards
-Dave

 

[Black Hand]

Blacken everything and look for rubbing. Also check that the lock-bolts aren't too tight and causing the lock to bind when in the rifle.

 

[don hepler]

If, there is no wood touching, then the only thing left, is the trigger bar. All guns with a hammer must have the sear move slightly down, before fully engaging the notch. Otherwise the notch would be negative degree, and would not hold. Most half cock notches are much more negative than the full cock, and the fly allows it to skip over the half cock notch, as it falls from the full cock position. The trigger bar should not be resting against the sear bar. You can shim the trigger down and test it.

 

[Vaino]

Have you checked the hole for the sear bar...both on the sides, the top radius clearance and bottom? This is a common flaw and the first time I took a LR to TOW's consignment sales, the trigger was pulled hard by Dave Riplinger when the cock was at half cock. He said this was the most common defect in MLers that he receives.....Fred

 

[Grizzly Adams]

Gently push the hammer forward at both half and full cock notches, both in and out of the gun and see if the hammer falls.

 

[crockett]

Could be the depth of the trigger plate is off. Is this a gun you built and inlet the parts?

 

[Hisownself]

Hammer will not fall either half cock or full cock when I push on it, in or out of the stock.

No, I did not build this gun. I bought it from someone who was the second owner himself and didn't know much about it.

 

[Hisownself]

Most of the stock removal I had to do (with the blacken procedure) was the sear hole. The sear was pushing on the side of the hole when half cocked (because as was noted the sear moves down further than in full cock). But it sets in there pretty free now.

 

[crockett]

Well, I'm going to have to think a bit on this one.
1. Push on hammer when at half or full cock and will not fall. No difference whether in or out of stock. That's good. way it should be.
2. Lock out of stock and put on half cock- push on sear- can't fire. Good, way it is supposed to be.
3. Lock out of stock and put on half cock but when you put the lock in the stock and use the trigger- it will fire (hammer drop) while in the half cock position. Off hand you would think the hammer/tumbler is somehow being moved back just a tad so the nose of the sear can clear when the trigger pulled. I'm trying to visualize if anything could be pushing the hammer slightly back as the lock is put into the stock.
Got to think on this :hmm:

 

[Zonie]

It sounds like the sear arm is touching the bottom of the clearance hole in the stock when the lock is installed.

If there is not enough clearance between the bottom of the sear arm hole and the sear arm, the interference will cause the sear to raise most (if not all) of the way out of the half cock notch.

The interference may not be happening at the mouth of the sear arm hole. It may be happening deep, down the hole where inletting black (or other transfer medium) may not be easily visible.

Try removing some wood from the lower side of the hole for it's full depth.
You might also make the hole a bit deeper while your at it.

I've seen sear arms get hung up on the bottom of the hole and do all sorts of unpredictable things when the lock is installed.

 

[Hisownself]

I'll check this tonight.

 

[tenngun]

Yeah I had a Davis lock that did that. Wasvery hard to detect.It just barly touched the inlet for the sear and would not smudge. I filed about a 16th of an inch off the bar and it worked fine :idunno:

 

[Stophel]

Assuming your trigger has clearance, and is not bearing on the sear at half cock and there is nothing else going wrong, then your problem is that you are pulling hard on the trigger at half cock. Stop doing that.

The half cock is NOT a safety. Repeat, it is NOT A SAFETY. On most, if not all, locks I have seen, pulling hard on the trigger WILL force the tumbler to move and it can go off from half cock. You may even break the half cock notch in the process. The half cock notch is there to hold the cock up so that the frizzen can be closed in preparation for the lock to be cocked and fired. It is meant to not go off with a normal pull on the trigger, however it is not meant to stop it from going off if somebody goes cranking on the trigger as hard as he can. :wink:

 

[Twisted_1in66]

Yup! The safety test we use at reenactments is to put the lock into half-cock position and hang the rifle or musket from your finger by the trigger. If it doesn't go off by its own weight against the trigger, then it is considered safe to use. If it goes off when hanging by the trigger, that rifle/musket can't be used until it's fixed.

Twisted_1in66 :thumbsup:
Dan

 

[crockett]

Never thought about that. Just asking....if you over tighten the lock's bolt could that sort of cant the lock just a hair- which on the sear arm/prong forces it down into a contact position?

 

[ZUG]

Assuming your trigger has clearance, and is not bearing on the sear at half cock and there is nothing else going wrong, then your problem is that you are pulling hard on the trigger at half cock. Stop doing that.

The half cock is NOT a safety. Repeat, it is NOT A SAFETY. On most, if not all, locks I have seen, pulling hard on the trigger WILL force the tumbler to move and it can go off from half cock. You may even break the half cock notch in the process. The half cock notch is there to hold the cock up so that the frizzen can be closed in preparation for the lock to be cocked and fired. It is meant to not go off with a normal pull on the trigger, however it is not meant to stop it from going off if somebody goes cranking on the trigger as hard as he can. :wink:

In response to Stophel

Yup! The safety test we use at reenactments is to put the lock into half-cock position and hang the rifle or musket from your finger by the trigger. If it doesn't go off by its own weight against the trigger, then it is considered safe to use. If it goes off when hanging by the trigger, that rifle/musket can't be used until it's fixed.

Twisted_1in66
Dan
I also think this is the answer to the "problem" but I've been wrong before :grin: .

 

[Hisownself]

This is good to know.

I wouldn't say there's excessive force when pulling the trigger, but I tried the hang test and it will not go off under its own weight.

This got me thinking about the mechanical advantage of the trigger and I realized I can get it to go off out of the sock if I really push hard on the sear. Too hard. So the trigger just provides mechanical advantage when I'm the stock and the required force is lessened.

So it appears the lock is performing fine. My other flinter (CVA 50cal Hawken) will not go off at all at half cock...no matter the force, so I assumed all half cock positions acted as a dead lock safety.

Thanks to all who helped with this!!!
Dave

 

[mr.flintlock]

Check to see if the very end of the sear bar is being pulled in to the stock when the lock bolt is tightened. This is often overlooked. Even slight contact of the sear and stock can result in the sear not fully engaging in the half cock notch of the tumbler.

 

[Alden]

Gee, I basically wrote something similar earlier and it's not here, only I referred to overtightening the lock nail...

:shocked2:

 

[Bobjim216]

I like the idea of shimming the trigger, especially if the lock won't hold at full cock. I had a similar issue on a percussion gun. I think it was a result of stock shrinkage over the years. Ended up taking a little off the top of the trigger bar.