Recoil causing lock issue

[Larry (Omaha)]

A fellow muzzleloader has a 10 gauge double percussion shotgun. He told me he has a problem shooting double clays because of a recoil issue. He is not overloading his charges, & even reduced them some. With both locks in full cock, after tripping the first lock, the second ends up in half cock. Reviewing this with him he stated all internal parts are snug, and has tried tripping both locks first. I have not seen or handled his gun, but wanted some input from anyone here who may be able to help.
Thanks

 

[ord sgt]

With both locks, look at the engagement of the sear and the full cock notch. It sounds like the sear does not fully engage the full cock, causing the tumbler to slip. It needs to be addressed by a competent gunsmith. It is a problem concerning safety.

 

[Crow-Feather]

I don't believe the second hammer should be cocked until the first has been fired. If the hammer doesn't stop at half cock, you are in for a big surprise.

 

[Robby]

Sounds like there is just enough inertia on the trigger to release the sear from the full cock notch. A stiffer sear spring would probably solve the issue. Filing or grinding the full cock notch a touch deeper would probably work too but the trigger won't be as nice as it probably is now. Learning to take it to full cock after firing the first barrel, to me, would be optimal and what I would be doing.
Robin

 

[Pete G]

Make sure that there is no wood interfering with proper lock function.

 

[hawkeye2]

A fellow muzzleloader has a 10 gauge double percussion shotgun. He told me he has a problem shooting double clays because of a recoil issue. He is not overloading his charges, & even reduced them some. With both locks in full cock, after tripping the first lock, the second ends up in half cock. Reviewing this with him he stated all internal parts are snug, and has tried tripping both locks first. I have not seen or handled his gun, but wanted some input from anyone here who may be able to help.
Thanks

That's not an unusual thing with hammer doubles including cartridge guns (the locks are basically identical). It's a sear nose/tumbler engagement issue and a competent gunsmith can fix it in a heartbeat. You should be able to fire the gun with both hammers fully cocked as designed without issue.

 

[Larry (Omaha)]

I don't believe the second hammer should be cocked until the first has been fired. If the hammer doesn't stop at half cock, you are in for a big surprise.

Obviously, you are correct if we were to leave it that way. Cocking the second lock after the first shot, will have the next clay long gone. The issue is how to correct it.
Thanks for posting

 

[Larry (Omaha)]

That's not an unusual thing with hammer doubles including cartridge guns (the locks are basically identical). It's a sear nose/tumbler engagement issue and a competent gunsmith can fix it in a heartbeat. You should be able to fire the gun with both hammers fully cocked as designed without issue.

Not seeing his gun, I was thinking about that possibility. Knowing that jumping into half cock is not unusual, makes it a little more palatable, but still needs to be rectified. I have a double flint, and never had that issue. This is a new one on this old man.
Thanks for posting

 

[hawkeye2]

I didn't mention it in my first post but most cartridge hammer doubles have rebounding hammers with no half cock so the issue manifests itself as the left barrel going off a millisecond after the right.

 

[Artificer]

With both locks, look at the engagement of the sear and the full cock notch. It sounds like the sear does not fully engage the full cock, causing the tumbler to slip. It needs to be addressed by a competent gunsmith. It is a problem concerning safety.

It may also be the sear on the second lock is worn too much and must be welded up and re-shaped or replaced.

Gus

 

[Larry (Omaha)]

It may also be the sear on the second lock is worn too much and must be welded up and re-shaped or replaced.

Gus

Gus,
Thanks, I received more information today. He has had the gun for about 20 years and it started malfunctioning about 3 years ago. As I said in the original post, it happens with either lock being first.

 

[Artificer]

Gus,
Thanks, I received more information today. He has had the gun for about 20 years and it started malfunctioning about 3 years ago. As I said in the original post, it happens with either lock being first.

OK, then this brings up other possibilities.

Since he said all internal parts are "snug," I wonder if he tightened the sear screws so much the sears are binding and thus not able to go fully into the full cock position? Many, if not most locks are not made to fully tighten the sear screw/s without binding. You have to back them off from "snug" to where the screws allow them to move freely.

If he is tightening the locks too tight in the stock, this will also cause problems over the years as it eventually crushes the wood supports and causes lock parts to rub in the lock mortices. Same thing can happen if one tightens the screws holding the triggers in place.

The way to find out what is going wrong begins with disassembling both locks to ensure the parts are not worn out and not overtightened. Then try assembling them and see if the parts are rubbing in the lock mortises. This can be checked by using lamp black or grease on the lock parts, tightening them in place, and cocking and dry firing each lock a few times. Then take the locks out to see if the parts are rubbing in the stock where they shouldn't be.

If the locks and or the triggers have been over tightened in the stock over the years and the wood crushed down too much, that can be fixed by gluing wood shims to get the distance from the parts to the wood correct, or even using glass bedding to build up the worn/crushed wood.

Gus

 

[ZUG]

Either it's a weak sear spring or a worn sear nose on the offending lock - take it to a qualified gunsmith for the fix

 

[Artificer]

Personally, since the owner mentioned the internal parts are all "snug" and he's having the problem in both locks, it would not surprise me if he overtightened the sear screw in both locks and just backing them off so the sears can move easily may be the only thing necessary.

Gus

 

[necchi]

Personally, since the owner mentioned the internal parts are all "snug" and he's having the problem in both locks, it would not surprise me if he over tightened the sear screw in both locks and just backing them off so the sears can move easily may be the only thing necessary.

I'm with Gus,, that's exactly what I was thinking. It's very common to over tighten as guns get older. It's possible the lock internal screws are too tight also. They may simply need proper lubrication too,, Clean, Dry and fresh oil every time before shooting goes a long ways to maintain these guns in good shooting order,, Keep it simple.

 

[Larry (Omaha)]

OK, then this brings up other possibilities.

Since he said all internal parts are "snug," I wonder if he tightened the sear screws so much the sears are binding and thus not able to go fully into the full cock position? Many, if not most locks are not made to fully tighten the sear screw/s without binding. You have to back them off from "snug" to where the screws allow them to move freely.


Gus

Very good point about his internal sear/screw tensions. After discussing this with him more and not seeing his gun, that is something I intend to look at if I see his shotgun. He is a good shooter, but ignorant about the mechanics of a lock. Since he has had it 20 years and said he checks the internal parts for getting loose, why were the first 17 years OK? Really at this point, it is just a guess without examining the locks, and function in and out of the stock.