Cocking arm not staying cocked...

[sooter76]

So I just got back from an NTC rotation and my lock that I had to send back to TVM for an unrelated reason was waiting for me. I reinstalled it today and attempted to do a dry fire to test it and when I cock the arm it immediately falls forward. It won't actually cock the arm. I pull it back and it falls forward.

Before I send it back for what will be the 4th time, does anyone have any advice on what I might do to correct the issue?

TVM has got to be getting as sick of me as I am of sending the same lock back to them...

 

[Black Hand]

Does the lock stay cocked out of the gun?
If yes, then the issue is likely due to wood interfering in the lock mortise. Check for rubbing...

Also, run the bolts in snug but don't force them. Sometimes too tight bolts cause problems too.

 

[sooter76]

It does...

And I tried not tightening the bolts all the way and yes I got the lock to cock properly, but that required taking the screw out about a quarter inch, maybe more.

 

[Black Hand]

Sounds like you have some wood interfering. You can soot the internals of the lock with a candle, place it in the inlet, screw down the bolts and cycle it by hand a few times. Remove and look for black - that will tell you where your high spot might be. Also look for a shiny spot on the lock internals and match it with the spot in the mortise. You should make certain to look in the inlet where the sear bar goes too, but you might need a flashlight.

If you feel comfortable, take a chisel and remove the wood carefully by scraping or paring. Repeat the process until the lock will stay cocked.

If this doesn't work, then the next spot to look would be the trigger and where it contacts the sear bar.

 

[Loyalist Dave]

OK well as Black Hand has mentioned, the wood has changed inside the mortise, or the part that was replaced is just a tad larger, OR both.

So when fully installed do you get a half-cock, but no full cock, OR does it not "catch" at all?

It's probably either, the sear isn't moving into the half-cock notch or the full cock notch, because the wood is depressing the sear slightly..., almost as if you're partially squeezing the trigger.

IF it goes to half-cock but not full cock, it may still be the sear being pressed upon, and it's barely engaging the half-cock notch, and so none of the full-cock notch.

Finally, if it goes on half-cock but not full, there is an off chance that the wood is preventing the cock from coming 100% back, so the sear can never drop into the full-cock notch. It is much more likely that the sear is being impacted than the cock not moving backwards far enough.

So I would clean and dry all the parts of the lock then reassemble the lock. Then I'd try the lock one more time just to be sure some tiny bit of crud wasn't the culprit. When and if it behaves as before, I would remove the lock, and then use candle soot, and blacken the interior parts of the lock, then carefully insert the lock and tighten it. Then remove it and see where the soot had transferred from the lock to the wood. Using an Xacto bladed knife, I'd carefully scrape, not cut, the areas that were black, to remove a tiny layer of wood. I'd repeat the process until black wasn't transferred, and then I'd try the lock for function.

The FIRST place I'd check is the tip of the sear lever where it goes 90 degrees to the trigger. If they replaced the seer lever, the tip of it may be going across the inside of the stock, and rubbing on the wall on the side opposite of the lock, OR rubbing on the hole drilled to accept the lever in the stock. Classic new part problem. If that's not touching the wall or the inside of the drilled hole..., then it's probably rubbing with other internal lock parts within the mortise area.

I hope this makes sense.

LD

 

[Zonie]

...

The FIRST place I'd check is the tip of the sear lever where it goes 90 degrees to the trigger. If they replaced the seer lever, the tip of it may be going across the inside of the stock, and rubbing on the wall on the side opposite of the lock, OR rubbing on the hole drilled to accept the lever in the stock. Classic new part problem. If that's not touching the wall or the inside of the drilled hole..., then it's probably rubbing with other internal lock parts within the mortise area.

I hope this makes sense.

LD

I'm betting it's the tip of the sear arm like you suggest.

If the length of the sear arm is just a few thousandths of an inch long it can bottom out in the hole in the stock that is made to clear it.

Usually these sear arms are a lot longer than is necessary so, assuming it is sticking out a long way, I would file off maybe 1/32" of its length and try it.

If it works with the lock resting in the mortise but it quits working when the lock bolt(s) are tightened, it's still a tad too long so I'd file off a little more.

 

[Artificer]

Sooter76,

Sometimes it is not clear what we mean when we talk about taking metal off the end of the Sear Arm. So allow me to link a picture of a Sear that shows it both as it sits in the lock on the left and as it looks from looking down from the top of the lock. https://www.trackofthewolf.com/Categories/PartDetail.aspx/0/1/LOCK-GPR-P-SE

In the link above, look at the view of the Sear on the right. The Sear Arm is the part that is facing down. You need to take metal off the end that is furthest down in that picture.

When I have to take metal off the end of the Sear Arm, I use a set of Dial or Digital Calipers to measure the length of the Sear Arm before cutting and write that measurement down. To take off the 1/32” that Zonie mentioned, you have to cut .031” off the Sear Arm.

You normally can’t cut the Sear Arm with a Hacksaw blade as the outer skin is hardened. You might be able to nick it with a file at that distance from the end and then hacksaw it off. The most difficult thing would be to hand file it shorter. There is an easier way to do it though.

If you have a Dremel Tool, you will need a Cut Off Disc Mandrel and some cutting discs. You can get these from most Big Box Hardware Stores at the Dremel Tool Display. Below is a link that shows a mandrel with a cut off disc in place and spare discs. https://www.aliexpress.com/item/Ne...andrel-1-8-For-Dremel-Tool/32677496785.html#!

You will need to scribe a mark 1/32” from the end of the Sear Arm. You can do that by marking all around the end with Black Magic Marker and then scribing/scratching a line on the marked surface.

For a cut off disc to work properly, you have to run the Dremel Tool on high and GENTLY touch the Cut Off disc on metal and with gentle pressure, it will cut the end of the Sear Arm off rather quickly. You want to keep the cut end of the Sear Arm fairly parallel to the inside surface of the lock plate, but it does not have to be perfect. I would STRONGLY advise you cut a couple of nails through with the Cut Off Disc to get the feel of it, before you cut the end off the Sear Arm.

Gus

 

[SgtErv]

Goodness, on top of an NTC rotation you have lock problems when you get homr. I feel for you. I spent four years in the Box!

Good luck! These guys are great with their advice. I read all this stuff just to learn

Sorry, ff - had to sympathize with a dust bowl survivor :rotf:

 

[mr.flintlock]

One thing I haven't seen touched on is that the sear arm may be binding against the triggers and preventing it from cocking. A washer placed on the screws between the top of the trigger plate and the bottom of the trigger mortise can fix it if that is the problem. Sometimes when the tumbler or sear or both are replaced, it can change the position of where the sear arm makes contact with the trigger.

 

[sooter76]

Turns out it was a trigger issue... I contacted a builder in Dallas and he diagnosed the problem pretty quick. He told me to set the rear trigger and see if it stayed cocked and if it did it was a trigger problem. I'm taking the the family to Medieval Times this Friday and I'll see him then for what I'm told should be a 10 minute fix.

 

[Loyalist Dave]

Super!

LD

 

[0311]

I think i have this same problem with my TVM Poor Boy. the lock works well if i set the front trigger before i lock it back, but if i dont, as soon as i go from half to full cock, it sets the cock instantly to the fired position. the lock works great though, out side the lock mortise.

 

[Grenadier1758]

When the triggers are set, the set trigger lever is lowered to lock under the front releasing trigger. That provides clearance for the sear in the lock to enter the full cock notch and then release the tumbler when the front trigger releases the rear trigger lever. Since everything works when lock and triggers are separated, there is an interface issue between the triggers and the sear of the lock. What that means is the triggers are being pulled too deeply into the trigger mortise and when the rear trigger is unset, the rear trigger lever is to high and the sear in the lock can't push the set trigger lever down. The trigger plate needs to be lowered to add some clearance between the trigger and the sear. The easiest trouble shooting test is to make a shim of cardboard to place under the trigger plate. Often that will get you the clearance you need for the lock to function properly.

Remember this one recommendation for muzzleloaders, most screws and bolts only need to be tightened to snug. Snug is only as tight as you get using one finger and the thumb on the turn screw. Over tightening will crush wood and cause problems. This applies to lock bolts, trigger plates, touch hole liners or percussion nipples, frizzen bolts and the little machine fasteners holding the tumbler and hammer. Anti-seize lubricant is a good choice to use on these threaded fasteners. Once the screw or bolt stops turning, its tight enough.

This problem of a double set trigger only allowing the lock to go to full cock when set is common enough that there is probably a sticky note here on the forum.

 

[45man]

Leave the metal alone. If a lock works outside the gun it is wood interference. Use a transfer dye, soot or Prussian blue and even lipstick to see where the problem is. The mainspring can be a problem too. So put the dye on it also to see if you need more wood relief. If you remove any wood make sure you seal it against moisture.
I built many rifles and the locks are a chore. Many factory rifles are not seasoned and will swell with moisture. Machine cut and not sealed.
Once we hunted a week in the rain and my friend had a new TC Hawken. I had my build. Mine came through perfect but his swelled and the finish peeled off. His had swelled 1/8" at the butt plate. It took me a few weeks to fix his.

 

[Grenadier1758]

While I agree that metal should be left alone, in this case, if the sear is too long, it is better to slightly shorten the sear arm. As noted in earlier posts, look to see what is rubbing since a replacement sear will likely have the arm too long.

Maintain the strength of the wrist by removing a little bit from the sear arm if the tip of the sear arm is rubbing on the inside of the lock mortise.

 

[Sidney Smith]

I'd bet TVM replaced the sear with a brand new one, and most likely it is too long as was mentioned. I had to cut my sear down on the new lock for my squirrel rifle. The stock once finished would probably have had less than 1/4 of wood between the outside and the inside of the sear hole had I left the sear the original length. You only need the sear to go maybe 1/4 inch past the center of the stock, if that much for the trigger to engage properly. Any more length on the sear bar than that is simply needless, and just causes the sear hole to be deeper than it needs to be.

 

[Rat]

"Cocking Arm". That's creative!!

 

[Bernard Streeter]

Had the Same problem. Had to put epoxy under the trigger group to extend the distance as it was inlet too deep. Problem solved.

 

[0311]

is it normal for the lock to function normally and then stop suddenly? I tested the lock out before firing, just to make sure it was making sparks, then stopped after a few shots were actually fired. I didn't tighten or loosen any screws or bolts before hand. after disassembly, it looks like it might be a bit of both, the wood interfering with the sear as straight across from it i can see a pock mark where it appears its digging into the wood. I also, cant get the lock to fit back into the mortise as the triggers also now look as though they are sitting too high and are blocking the sear bar from going back in, so i have to set the rear trigger to get lock to fit back in (i have not tampered with the triggers at all yet). i have owned and shot many other firearms in the past, but this is my first flintlock so I'm sorry for the stupid questions. Is there something that i may have unknowingly done, that would cause these thing to happen so suddenly?
Edit: it WILL lock into the half and full cock position, if i set the trigger before i start the cocking process.

 

[Grenadier1758]

I don't think here is anything you have unknowingly done to cause this other than using the rifle and having things settle in place. This is part of learning about your rifle and getting it through the learning process. Based on the fact that the lock goes into half and full cock if the trigger is set and you can't install the lock unless the triggers are set, indicates that the triggers are too high in the mortise. The rifle will work in the manner of a singe lever double set trigger. It is a relatively simple matter to shim the trigger plate to lower the triggers.

By the way, don't be sorry for questions. That's what the forum is best at, answering questions. Some of our answers may need to be thought about, but diverse opinions provide greater knowledge.