Half-cock won't hold against trigger pull

[tparker2006]

Hi,

I'm just finishing up my first gun build. It is a Chambers York kit and it uses the Golden Age Germanic lock. After putting the final coats of finish on the stock I assembled it and found that now the lock will not hold on half-cock.

It will catch and stay in the half-cock position however I can pull the trigger and release it. As I pull the trigger I can see and feel the cock rock back slightly and then release just as if it is in the fully cocked position. Not a very good safety needless to say. While building the gun I did get the lock installed and tuned so that it worked perfectly. The current problem has only cropped up at the final assembly stage.

Here are a few of the things that I have tried to remedy the situation.

• I have blackened the entire lock, installed it and cycled the cock through the full range of motion. I did not see any spots inside the lock cavity which looked as if the mechanism might be touching/rubbing which might prevent proper operation.
• I have dis-assembled/re-assembled the lock several times, checking for rough spots on mating surfaces and lubing in the process. No difference.
• I have removed the trigger plate which allowed the trigger to swing freely. This proved to me that the trigger was not applying a slight pressure on the sear which would not allow the half-cock position to fully engage.

I am out of ideas as to how to resolve this problem. Anyone have any suggestions that I can try out? BTW I did try searching this forum for any topics involving this subject without any luck. I kept coming up with either 0 search hits or 500, neither of which seemed correct.

Thanks for any help,

Tim

 

[Roy]

If the lock works fine out of the gun... goes in half cock and stays there when pressure on the sear is applied... it is either hitting wood or the trigger. Places to check are where the hump on the mainspring (the part that contacts the tumbler) could be hitting the wood in between the bolster and mainspring... or the sear is touching the sides or bottoming out at the bottom of the hole. Totally remove the trigger to just to be more than sure... Its there somewhere. Been there and have done that several times.. :v :thumbsup:

 

[Stophel]

The half cock is NOT an absolute safety!!!! You WILL be able to pull the trigger and the cock will fall. Now, it should take a pretty hard amount of pressure, but it is going to lift the tumbler up and out of position. Some tumbler designs do this more easily than others.

The half cock simply holds the cock at...well, at half cock. DO NOT rely on it as a safety. DO NOT pull the trigger when the gun is on half cock (even if you can't make the cock drop, you may well break the hook on the tumbler or the sear nose).

I know a lot of military groups will have you hang the gun on your finger to see if it will drop from half cock....this is not a good idea.

Now, beyond that, you may have a problem with the sear nose not going fully into the notch in the tumbler. The Siler tumbler often can stand to have some filing done to it so that the sear will fit into the notch easily without wanting to wedge the hook off the tumbler.

 

[Roy]

:thumbsup: right you are, but it would take a good deal of pressure. :v

 

[paulvallandigham]

Tim: Give Jim Chambers a call. He will help you with the lock. And he probably knows better than most of us why or what it is you have done that is interfering with the half cock notch working properly. Every gun I own has a half cock notch that can take the entire weight of the gun and not slip. You better not be able to drop the hammer from any half cock notch that I have!

 

[oldarmy]

You have some wood rubbing somewhere in the lock area that is causing it to do that.
I would bet it's where the sear bar enters the stock. Check to make sure the searbar is totaly free of any wood contact.
Try taking the trigger out of the stock. Insert the lock, tighten it down to what you normaly do.
Then run the lock throught half/cock..full/cock.
Use a screw driver to trip the lock.
If the lock works fine, Then your problem is the trigger is putting too much upwards pressure on the sear.
You need to lightly file the trigger down some.
If the lock doesn't work with the trigger removed and it's tighened down, Then look for rubbing spots after removing the lock.
Good Luck,, and remember it happens to everyone.
Take your time and you will figure it out.

 

[oldarmy]

heres another thought.
If you tighen down the bridel screws too tight, some times that can cause the sear to act funny.
The sear needs to be able to move freely.

 

[keith44]

:shocked2:

I had this problem on my Traditions Hawken a few years ago, the sear had broken and would not fully engadge the tumbler's half cock notch. On replica guns like yours, and in the spirit of guns like mine the half cock notch is deeply cut and captures the sear lever to prevent trigger pull from releasing the sear with out the hammer being pulled back. check to be sure that these pieces fully engage, and are properly formed, and not being held out of engagement by any debris, or varnish. If you have broken the sear you will have to re-shape it with a dremel with a drum sander attachment, or have it re-shaped by a gunsmith.

 

[ricklandes]

I think you are right on track with the sear bar. My guess is it may be rubbing the back of the hole to the top of the trigger or it's hole is not deep enough. A small piece of wood is the trouble.
The finish may also need a bit of cleaning out around the inlet edges. There may be just enough to cant the whole works enough to bind the sear bar...
I agree call Jim

 

[Vaino]

When TOW receives a rifle for consignment sale, the trigger is pulled when in half-cock w/ a moderate amount of force and if the cock falls, it's a safety issue w/ them and needs fixing. What they're checking for is an incomplete seating of the sear nose into the half-cock notch for whatever reason and evidently it happens often enough to warrant checking. I have witnessed this seeing I deliver my LRs to them, not trusting a delivery service....Fred

 

[Stophel]

I think you all may have hit on it. The sear is usually at it's lowest position at half cock. When the lock is on half cock, there may not be enough slack in the trigger to accomodate this, and the trigger is bearing up on the sear, keeping it from going into the notch fully.

 

[tparker2006]

Thank you all for the great responses!
Even though I agree that the half-cock position should not be considered a 100% safety I do believe that it should resist a lot more trigger pressure than I am seeing with my current problem. Certainly in comparison to other flintlock rifles that I have had my hands on. I would almost expect something in the lock mechanism to break before it just releases the cock from the half-cock position.

So far the general consensus is that I have some interference with the wood inside the inlet area so that is what I am going to check again when I get home tonight. I am going to enlarge the hole that the sear bar goes into first and see if that has any affect.
I already eliminated the trigger bearing against the sear as the possible cause by removing the trigger plate which effectively allowed the trigger to swing forward so that it was no where near the sear.
I've examined the half-cock notch and the sear pawl that goes into it carefully and it looks as if it seats properly (at least when out of the gun).
I have even set the lock on half-cock with it out of the gun, verified as best I could that it is engaged and then installed the lock into the gun. A fairly light pull on the trigger will then still release the cock.
As a last resort I will try contacting Jim Chambers to see if he has any suggestions.

I appreciate all of the help that everyone has provided here and I'll be sure to let everyone know what the problem was WHEN (not if) I find it.

Thanks,
Tim

 

[tparker2006]

I finally called and spoke to Jim Chambers. He repeated exactly what Stophel said earlier. The half-cock position is NOT an absolute, with enough pressure it is possible to release the trigger. Depending on the position on the trigger it will take more or less pressure. The way I built mine it obviously takes less pressure. It's not a big deal, the cock will not fall accidentally in this position as long as there is no pressure on the trigger.

Thanks everyone. Now to go out and shoot it!

Tim