Percussion lock problem

[hankfannin]

I have a fairly new percussion lock that keeps dropping into the half cock position when I try to fire it. If I mash the trigger back it fires OK. When I try to squeeze the trigger it stops at half cock. It does this mounted or not so it's not binding on any wood. I don't want to mess this lock up by doing any filing or reshaping of the tumbler or anything until I get some advise and know what will work.

Thanks,

Greyhawk

 

[Flint311]

Almost sounds like the "fly" is missing from the lock. It's a very tiny L-shaped piece that moves the sear past 1/2 cock when the trigger is pulled. What type of lock? This may help in diagnosing the problem. Good luck!

 

[Rifleman1776]

sounds like the "fly" is missing from the lock. It's a very tiny L-shaped piece

The "very tiny" part needs to be realized by beginners or they can get lost in a blink. There may be other causes, like the sett screw adjustment, bad inletting causing pressure and more. We need to see it to really help. Take the lock out and send some pics.
hotoSmile:

 

[Melnic]

My only similar experience was the screw that holds the lock on was so tight, it went through and was contacting the hammer. I loosened it and it worked fine. Then took it out and ground down about 1/16" and it was fine.

 

[necchi]

What's the make?
TC, CVA, Traditions, L&R,,,?

 

[hankfannin]

I thought of that also but this lock doesn't have a fly. Actually I don't know the make. I bought it at a swap meet. I think it may be off one of the Traditions rifle kits.

Thanks

 

[necchi]

Does it look like one of these?
Spanish, un-bridled and bridled.

 

[crockett]

Your "gentle" touch may actually be recreating the same situation as a set trigger that requires a fly. The lock was designed for the trigger to be pressed back and held back until the rifle fired, otherwise the undercut half cock notch will engage. The other, as mentioned, is the too tight lock bolt.

 

[hankfannin]

Yes that's the one, the unbridled one but the good news is I just fixed it. I found another tumbler in my box of spare parts, one with a fly. Switched tumblers and end of problem.

I'm always learning things on this forum guys. Many thanks.

Greyhawk

 

[hankfannin]

Necchi,

After changing tumblers the lock works just fine, except for about a mile of trigger creep. Can I get rid of that by adjusting the screw on the tumbler? What I'd like is a nice crisp trigger pull with little to zero creep. Is that possible with this Spanish lock.

Many thanks for taking the time to take those photos and posting them. That helped a bunch.

Greyhawk

 

[Artificer]

Not Necchi, but....

Trigger creep is a product of the amount (length) of sear nose engagement on the full cock notch (how much length the trigger nose has to move before the nose is pulled free from the notch) and/or the angle of the full cock notch. Changing the full cock notch angle is NOT something most hobbyists should attempt.

It looks like that screw is designed to push the trigger nose further down the notch the more you screw it in. That will give you a lighter trigger pull and less creep the more you screw it in. HOWEVER, you don't want the sear nose BARELY being held by the full cock notch or it will slip off and won't hold when raising or bumping it.

What you may try is screwing that screw in until the bottom of the sear face is even with the bottom of the full cock notch. That should be enough sear contact to hold and not go off by slapping the rear of the buttplate. If that is not enough sear contact to do that, then you unscrew the screw until it does.

Let us know how that works.
Gus

 

[Melnic]

I recently adjusted my Lyman and CVA trigger to be similar to my Thompson Center which had a nice crisp trigger. Guy at a Sunday ML shoot suggested I do it.

The procedure I followed was one I read on the interwebs:

(Remove trigger guard)
1) With Hammer DOWN, Set trigger
2) Turn front screw in (CW) until trigger releases
3) Turn front screw back out (CCW) one full turn
4) Test

I ended up turning it back in I think 1/4, so it was 3/4 Turn out.
Both were about 1lb pull and very crisp.

The screw on the Lyman would not let me go in as much as I needed so I found a 2.5mm cap head screw I already had and used that. I dabbed a bit of blue loctite on the upper end (so not to wick down into the trigger area) to keep it from moving.

It was helpful to remove the trigger group and turn the screws while reading what they do in order to best understand what was going on. Yes, you don't want it so far in that it becomes dangerous and watch where you point it when you set the trigger as always.

 

[hankfannin]

This lock has a single simple trigger, not a set trigger so I'm limited to what I can do. I'll adjust the screw on the tumbler as you advise until I can get the shortest travel possible and still be safe. I'd say that's about all I can do unless I go with a different trigger,maybe a double set. Thanks to all.

Greyhawk

 

[rafterob]

The lighter you adjust the trigger pull the more creep you will get with those set ups. You can get used to the creep pretty quick. A hard trigger pull is harder to deal with in my experience.

 

[Zonie]

IMO, a "safe" amount of sear engagement is when the full thickness of the nose of the sear is still fully engaged with the notch in the tumbler.

Any less engagement is asking for trouble.