Mainspring fitting issue

[JGD88]

Hi all,

My first time trying to work on an original lock so I wanted to ask for some advice. This is one of the locks from IMA in their Brown Bess kits. It was delivered already cleaned up and was adverstised as being functional. I cannot get it to go to full-cock. Half-cock is fine, but the mainspring appears to be putting up too much resistence, or the tumbler is not the right fit?

The mainspring protudes out the bottom of the lockplate so I cannot inlet it either. My thinking is it is either a replacement mainspring that is a poor fit, or the tumbler is a replacement and a poor fit. I know this might need additional pictures and describing but any input would be much appreciated. I have attached an image that shows how far it protrudes out the bottom of the lock. Is there anything I can do to force the mainspring up? Trimming it has to be out of the question, so then that leaves either a replacement mainspring, or a new tumbler...

I contacted IMA 2 days ago in the evening and have not yet had a reply. I will give them over the weekend before contacting them again.

 

[Loyalist Dave]

Hi all,

My first time trying to work on an original lock so I wanted to ask for some advice. This is one of the locks from IMA in their Brown Bess kits. It was delivered already cleaned up and was adverstised as being functional. I cannot get it to go to full-cock. Half-cock is fine, but the mainspring appears to be putting up too much resistence, or the tumbler is not the right fit?

Yeah, that's wrong (referring to the photo). That spring is incorrect if it's flexing below the edge of the lock plate. I also don't like the enlarged hole for the tumbler on the tumbler bridle nor the sear, as the sear looks worn.

I can't tell if the bridle goes below the lower edge of the lock plate, but from the angle it looks like it does.

I think they took a spring off another lock and a tumbler, and got the lock they were working on to go to half-cock and said "fixed".

LD

 

[Erwan]

It looks like a lock very worn with and ovalized backplate, and it's also possible that the rocker arm curve plane is badly worn too, certainly the sear and notch by the same way......
All this could perfectly allow the main spring to drop well below the correct position and reach the end of the curve plane, in this case everything is becoming too low, and the spring seems to be the only one at fault, but this is not the only problem of the lock...
LD's painting shows the problem: few month ago I rebuilt a completely worn out lock like this (rocker, curve plan, main spring and plates, etc) for a dueling pistol...

That's what I think about this...

 

[Artificer]

It may also be the angle, but it even seems like the rear of the bend of the Sear Spring sticks out beyond the edge of the lock plate.

Personally, I would send the lock back to IMA for them to fix or replace with a serviceable one.

Gus

 

[hawkeye2]

The spring is almost ready to slip off the tumbler. If that happens when you fire the gun the spring could break out the stock in that area. I have seen where it has happened on original guns. A collection of worn parts that don't play well with each other.

 

[ohio ramrod]

another voice for collection of worn parts that don't fit each other.

 

[Steve Martin]

Hate to "pile on" but that lock is worn out. Send it back to IMA.

 

[oldwood]

If your stuck w/ the lock and can't send it back , you might try soldering a small piece of metal on the underside of the hammer stop. That will prevent the main spring from going below the lock plate. However , if the tumbler bearing is worn out , the lock will require a machinist to correct the mess...............oldwood

 

[dave_person]

Hi,
That lock has a lot of problems. I believe the mainspring is a replacement and the hook is not shaped properly. The shoulder on the flint cock may be worn allowing the tumbler to rotate too far forward. Who knows it may be a poorly fit replacement too. The tip of the sear appears to be worn down and the bridle spindle hole is too large, however, I think that may not be wear but the lock has an incorrect tumbler. The spindles on the tumblers of Bess locks are as large as that hole. I would send it back for replacement. Otherwise, I would rebuild it with new internals from TRS. The problem wit locks like this is that you usually cannot just fix one thing. It is a system or network of parts and you find one problem leads to others.

dave

 

[FlinterNick]

I just rebuilt an old pedersli Grice lock with third model bess castings from the Rifle Shoppe. The mainspring fit like a glove, other than having to heat and tap the foot/paw very slightly to get it where I wanted it. Replaced the Sear too. The mainspring, sear, tumbler and bridal on this 1970’s grice lock by pedersoli seem to almost be identical to a third model, other than the sear spring which is longer. The only problem I had was the need to remove a little bit of wood in the mortise by the forward lock bolt, negligible effect.

 

[FlinterNick]

Hi all,

My first time trying to work on an original lock so I wanted to ask for some advice. This is one of the locks from IMA in their Brown Bess kits. It was delivered already cleaned up and was adverstised as being functional. I cannot get it to go to full-cock. Half-cock is fine, but the mainspring appears to be putting up too much resistence, or the tumbler is not the right fit?

The mainspring protudes out the bottom of the lockplate so I cannot inlet it either. My thinking is it is either a replacement mainspring that is a poor fit, or the tumbler is a replacement and a poor fit. I know this might need additional pictures and describing but any input would be much appreciated. I have attached an image that shows how far it protrudes out the bottom of the lock. Is there anything I can do to force the mainspring up? Trimming it has to be out of the question, so then that leaves either a replacement mainspring, or a new tumbler...

I contacted IMA 2 days ago in the evening and have not yet had a reply. I will give them over the weekend before contacting them again.

Almost everything on this lock seems misaligned.

The bridal arbor hole looks like it was drilled or opened too much, i’d replace it with a casted bridal, third model.

The sear spring screw looks higher, which makes me wonder if the lug slot is worn or too large, might want to do a small weld deposit there on the plate and re-cut / mill.

The mainspring looks like a third model mainspring I have here with me, but I can’t tell if its the tumbler turning too far or the flintcock shoulder being peened over from use. It could be a combination of both causing the spring to move beyond the plate.

Agree with Dave, the seaR nose looks rounded over, needs a chamfer edge.

 

[erhunter]

I would send that back for sure. It has a lot of problems.

 

[GREENSWLDE]

I would send that back for sure. It has a lot of problems.

I very mush agree. SEND IT BACK. Your never going to make a Silk Purse out of that Sows Ear.. OLD DOG..

 

[Erwan]

I've rebuilt locks that are just as worn and even more with missing parts, but it's never as good as a new...
So if you really don't have the possibility to work on it (location, tools etc.) or if you don't have the skills, it's better to give up right away and send that pot of gremlins back to where it came from.