Hi,
Well, I reworked the lock. I may make a new stronger mainspring but I will leave the reworked original on for now. It is a little weak and I initially thought it was too stout on the lock as it came. However, that heavy feel was not the spring rather the shoulder on the post of the tumbler did not protrude above the lock plate so when you tightened down the tumbler screw, you tightened the cock against the plate! No wonder it was hard to cock the lock. The fit of the frizzen to the pan was bad enough that 4F powder could leak from it. The tumbler post was not perfectly round and the hole in the bridle was not true with the tumbler hole. However, there was plenty of excess metal to work with considering the plate was almost 1/4" thick. I decided to thin and flatten the plate, reshape it more like those on Hills' guns and replace the flintcock, tumbler, bridle, and sear with Chambers Siler parts. Here is the original lock.
First, I had to drastically thin the plate from both sides, clean up the surfaces and file a bevel on the outside of the plate. I used my coarse single cut files and they did a speedy job of it. I don't have a milling machine so I work with hand tools but I can file very flat, even, and clean surfaces. I put a bushing in the tumbler hole because the original hole was not perfectly round and too large for a Siler tumbler. I've done this before. I drill the hole to 5/16" then counter sink both sides of the hole. Then I cut a 5/16" steel plug to fit in the hole, flux it, and solder in place with low temp silver bearing solder. Then I peen both sides of the plug to fill the counter sinks. This works really well even if I want to later case harden the plate. During that process, the solder will flow again but the bushing is held in place by the peening and when the plate is quenched, the solder simply congeals again. The photos show the plate with the bushing in place.
I file the bushing flush and then fit the bridle. I used the existing hole for the upper screw anchoring the Siler bridle. I had to fill the sear hole just like I did the tumbler hole. Then I used the bridle to mark the location of the sear hole and drilled and tapped it. I installed the bridle and used the tumbler spindle hole to mark the center of the new tumbler hole in the lock plate. Using my drill press, I drilled through the bridle hle and through the lock plate. Then, without moving the plate in the drill press vise, I removed the bridle and drilled a hole through the plate just a hair smaller than the tumbler post. I then reamed that hole to fit the tumbler. It came out great. I reused the sear spring, which was a very nice forged spring and could be bent a little to work perfectly. Now, I was able to install the tumbler, sear, bridle, and sear spring and make sure they all worked. I selected a flintcock from a deluxe Siler lock to replace the round-faced original. It fit perfectly with a little filing and looks just right. I reused the top jaw from the original lock after reshaping it a bit.
Next I had to work over the frizzen. I annealed it and reshaped it. Then I fit it to the pan to close any gaps. I came out well but could be a little tighter. I am not sure if I will worry about the fit any further. Next I worked over the frizzen spring, reshaping it, closing the bend, and cleaning up the uneveness of the steel leaves. I reshaped the finial. I polished it, hardened and tempered it and installed it on the lock with the frizzen. Next I worked over the mainspring and reshaped it to give it a little more strength. Its architecture is fine but it may need more thickness. I may have to make a new spring. Anyway, the lock works very well, has a nice smooth feel and function. I would say it is now at least the equal of any well assembled Siler lock. It will need some tuning and cosmetic work but it is ready to be inlet on Josh's new fowler. It has a nice rustic, hand made look much like the locks typically found on Hills' guns.
dave
