Some Thoughts on Lock Making

[mooncoon]

I recently decided to take on the challenge of making a percussion lock to fit a rifle which was missing one. It was definitely a challenge at times. The rifle is stamped W & E Jacot, Birmingham on the barrel and appears to be original to the stock but my guess is that the barrel was imported to the US because of the stock design and the wood appears to be curly maple stained and aged to a dark brown and initially appearing to be walnut. At first glance the lock recess appeared to be of average size but the lock is actually a little on the small side and the front portion of the lock plate is relatively short which meant that the mainspring had to be fairly short. The short length of the mainspring turned out to require that the lower arm of the spring had to be a little thinner than average because its short length shortened the lever arm in terms of the effort to bend the spring up and down. The rear lock screw turned out to be farther back relative to the back of the barrel and that sort of forced the tumbler of the hammer to be farther back and that had implications on the length of the hammer in order for it to strike the nipple properly. I chose to make the shaft the hammer fastens to, a bit larger than normal because those shafts have always seemed fragile to me. The significance was that the pivot point had to be lower which added to the length of the hammer. Both features meant that the sear was farther back which meant that the length of the arm of the sear was short and therefore required more pressure on the trigger to release the hammer Perhaps worth mentioning that I have built a couple of locks before but more or less copied existing locks and in some cases used cannibalized parts so didn't run into any surprises with them
What was surprising also was that the gun had non adjustable single set trigger. The trigger guard was pinned to the stock which more or less meant that you are more or less stuck with however much tension the trigger was built with.

cheers mooncoon

 

[mooncoon]

Something surprising; I googled Siddon set trigger on the off chance that there might be some information on the web --- I got a hit saying that L & R and Davis made triggers with Siddon stamped on them and theirs are adjustable because the screw which secures the spring that pushes the trigger sear up and into engagement is mounted with the head on the outside of the trigger plate. Tightening that screw puts more tension on the trigger sear and increases the trigger pull. On the gun pictured above, the screw pointed down and was threaded into the trigger plate and could not be adjusted while in the gun. I am kicking myself that I didn't do the google search a few days ago and could have changed the trigger to function like the modern ones

cheers mooncoon

 

[jpc]

Interesting project and thanks for sharing mooncoon ☺

 

[NorthCoastBigBore]

You do some nice work and truly interesting builds Mooncoon. Thanks for sharing

NCBB