Black Powder Lock - Hammer Screw Repair?

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Who out there might be able to do the following work and/or locate the right part for this old black powder shotgun?

- The gun: W.G. Rawbone 20" percussion coach gun, 10 gauge

- The problem: screw head for the screw that holds one of the hammers on has broken off

- The work: (a) back out the tiny screw shaft, if possible. (b) locate or fabricate a replacement screw with a tiny bit of scrollwork. (c) install new screw

She is a small screw and and screw shaft - delicate work to be done. Gun is not a high value gun, but she's a nice historical piece and I want to fix her.

Any thoughts please let me know.

Thank you all!
 
It was looking at similar jobs in other fields (mostly Brit bikes, but also in guns) that drove me in to metalwork and machining as a hobby.

FWIW, about any competent metalworker can pull out a broken off screw and make a replacement. It really is going to be a chore on your part, I think, to fine someone that you can live with the cost of their services though.

Factor for an hour or so at Shop Rate, for the extraction, and another 1 to 1 1/2 hours to make the new screw.

Could be a LOT less. But if you expect bad, and it doesn't come... You are ahead!
 
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I am working on this lock right now - it has the same problem as the OP's.
The snapped off screw might or might not be hard. Haven't determined this yet. Still trying to source a replacement flintcock.
Basically, what I will do is remove the tumbler from the lock, and drill the screw. I will start with a bit smaller than the screw diameter. Perhaps it will be possible to turn it out then. If not, I will use larger and larger drills until I can pick out the remains of the screw. I will not touch the threads in the tumbler shank. I do not want to damage the tumbler. It will make replacing the screw easier if I can get the remains out intact. Then it is easier to determine diameter and thread pitch. The pitch may or may not be a modern one. It might be close enough that a replacement screw can be made using a modern die to cut the threads. If so, it is a straightforward job make a relacement on the lathe. If I cannot get the broken screw out in one piece, I will turn a little piece of hardwood into the hole, to pick up the diameter and pitch.
 

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tiriaq,
I do not have anything near your level of experience or expertise, but have a question. Would it not be best to start with a left hand twist drill in the hope it would back the stud out?
 
That is certainly an option, particularly if the screw is not seized in place. I do not have a left hand bit that size. Not having found a flintcock yet, there is no rush; I should source an appropriate LH bit, give it a try.
When a screw is broken off in a 200 year old lock, there is no way of knowing why it is broken.
 
Log Cabin shop carries 2 different sizes of lock screws in 4 different thread pitches. Pretty nearly anyone that carries locks will carry them.

What is the diameter (roughly) of the screw you are dealing with? If it is too small for an easy out - drill it out and go up a size.

if it needs some engraving there is a guy in Etobicoke that does hand engraving & will be able to match. ( https://www.bradshawgunengraver.com/ )
 
Many tumbler screws are decorated with a simple sunburst pattern. This can be duplicated with needle files. My lock has only minimal engraving, so that would be fine. Haven't measured it, but probably somewhere in the #5-#6 range.
 
This is all TERRIFIC information and guidance - thank you! I will not try this myself. I will pay someone more competent than me to do it.

I do have the basic sunburst pattern on the screw - very glad to hear that is common, and not to hard to replicate (or maybe purchase?)
 
I would lean towards annealing the tumbler first if there is any indication of the screw being hardened. Afterward reharden and draw to around 690 to 700 F in molten lead. You might also be wise to soak the annealed tumbler in Break Free or similar for a day or two. I have made a small square taper type easy out from a chain saw file to try unscrewing with. If the screw is hardened and the drill slips sideways, it would probably be harder to end up with a centered hole

cheers mooncoon
 
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