I'm Puzzled, Cap Lock Question

[Eddie2002]

I'e been working on a Marathon 50 caliber cap lock which was probably made back in the 70's. It's nothing special just a 50 dollar pawn shop pickup that needed a home. The problem with the gun is that when it is fired the hammer gets stuck on half lock instead of going all the way down to the fired position . The lock is similar to the Tradition cap lock setup with the nipple on the side of the breach plug and the trigger is a double set.
What has me puzzled is that the hammer will go to the fired position and not get stuck at half cock when the lock is out of the stock. I checked and couldn't find any tight spots or wear marks on the stock where the lock mounts. I have also checked the double set trigger and it seems to be working just fine.
It seems that the sear isn't being held open long enough to allow the mechanism to move past the half cocked position when the lock is in the stock.
I haven't tried adjusting anything yet, don't want to fix it broke.
Any ideas as to where to start or what to check?
Thanks

[Col4570]

When the Lock is out and you set it off ,releasing the sear you hold it open longer that when in the stock.Idealy you need the lock tumbler modifying to take a Detent (Fly).You may get away by adjusting the Set trigger to a heavier pull which might allow the tumbler notch to be overridden by the sear.Good luck.

[bedbugbilly]

Also - while it could be a number of things - you've checked to see that the lock mortise is clearing the moving tumbler, etc. - but - put some soot or something that will transfer and check it. Over the years, I have seen what you are describing happen when the lock bolt is overtightened, pulling the lock into the mortise where just a "kosh" too much causing it to bind - if too close, even high humidity can sometimes cause the wood to swell.

Try what Col4570 suggests on your triggers. If all the parts are original to the gun, and it came with set triggers, I would think it would have a fly in the tumbler unless it was removed at some point.

Perhaps you could post some photos and that might be of help as well.

[Eddie2002]

I just took a look at the lock and it doesn't have a fly on the tumbler and looks like it never had one to start with. I adjusted the set trigger with no luck, even removed the set trigger adjustment screw but the lock still stops at half cock. All the clearances in the stock look fine and the problem still occurs with the mounting screws loose.
I don't know much about the gun except that is was build by Monarch in the late 60's or early 70's and looks like it came with the set trigger. Somebody had monkeyed with it by cutting the stock down and all around bubba'd it so maybe the trigger assembly was an add on sometime in it's life.
One thing I did notice is when I press the set trigger forward with the adjustment screw all the way out and fire the gun the hammer goes all the way into the fired position like it should which makes sense because the set trigger would be getting pressed against the sear pin.
I'm starting to think that double trigger assembly isn't compatible with the lock and I either need a single trigger assembly or a fly installed on the tumbler to make the gun safe.
I'll get some pictures together.
Thanks

[oldracer]

Grab a bright red tube of lipstick and pull the lock and trigger out and clean any oil. Then rub the lipstick on any parts that move or stick out of both assemblies. put them back together and try the lock and hammer assemblies. If there are any places that are rubbing the lipstick will transfer. You could also paint the inside of the stock cutouts with white paint such as correction fluid and then assemble the parts and dry fire. The paint will rub off if there is interference. I use the red lipstick when I and fitting parts to my muzzle loaders as it is easy to remove wood but really hard to put it back!

[Omnivore]

Any lock that's to be used with a set trigger needs a fly. You wouldn't see that it ever had one unless you got out a magnifying glass after cleaning the tumbler really well, AND knowing exactly what to look for. In any case, don't mate up any lock with a set trigger unless it has a fly. So any way you look at it, you need to install a fly.

And yes, I have a rifle with a single, standard trigger, and the half cock notch sort of nicks the sear every time the tumbler drops from full cock. I can see that happening on any lock having a tumbler that's been made wrong, or has been altered inappropriately. That's sort if irrelevant though since you're mating your lock with a double set trigger. It needs a fly regardless, and a properly installed fly will make that tumbler work in any circumstance.

[Col4570]

I had the same trouble with a Euroarms Enfield,I eventualy cut the Tumbler and made a Fly,it fixed the fault.
You can either slot the Tumbler or the Bridle.If you slot the Bridle you will need a wider Sear Nose.That Rifle did,nt have a Set Trigger but always dropped on Half Cock.

[Eddie2002]

Thanks for all the help, I've a CVA caplock with a set trigger. I'll pull the lock and trigger out of it and compare it to the Monarch to see if I can spot any differences.
Don't know about installing a fly on the tumbler, it might be more than I can do.
After a quick comparison of the two locks I'm positive the Marathon came without a fly on the tumbler. Don't know of any gunsmiths in the area who could install a fly on the lock. If it's not a black tactical nobody around here will work on it.
Guess I'll make a single trigger setup.

[Eddie2002]

I was checking Flea-Bay and there are a bunch of CVA tumbler and fly assemblies for sale on it. I plan to compare the two locks and see if the tumblers are interchangeable.
From what I've been able to find so far making a fly doesn't seem that difficult so I'll give that a try first. Maybe use a 1/4 inch bolt to start with, turn and file it down to size.
Plan B will be Flea-bay.
Thanks again for the advice

[Ballistics in Scotland]

Is the trigger designed to let you use it unset Some are and some aren't. If the problem only arises when the trigger is set, that more or less eliminates the fit of the wood as the cause of the problem, or at least limits it to interference with the movement of the settable trigger. It might be that a stronger spring on that trigger to make it hit harder, or clearing wood on which it grazes, would solve the problem. That would increase the pull, but probably acceptably.

[Hanshi]

A double set trigger really does need a fly in the lock for proper performance. Conversely, a single trigger is sometimes hindered by one. My flint pistol had a "catch" when the trigger was pulled and the hammer was at full cock. This resulted in many FTF due to a light stroke. I removed the fly and the problem was fixed.

[Eddie2002]

Hanshi, I built a flinter pistol with a single trigger and used a rifle lock that had a fly and had the same problem. I didn't remove the fly, just stopped shooting the pistol as much. I'm thinking about stripping the parts off the pistol and building a rifle, the pistol just didn't turn out right.
B in Scotland, the regular trigger doesn't work unless the set trigger has been set.

[Col4570]

Check out Page 4 item 63 My favourite Firearm,The set trigger of unusual design works well with that rifle in both Set and Unset modes.