The right side lock with the broken spring, and a bridle that had been scarred up by the wielding of an ill-fitting screwdriver by an uncaring slob of a gunsmiff.
You mean the screwdriver shouldn't be wider than the screwhead?, asks Bubba. Left and right were similarly damaged.
The bridle after cleaning it up as much as practicable.
The spring that powers the safety sear is a single leaf with an eye that surrounds the foremost upper bridle post. It also has a tab that keys into a slot in the lockplate to keep it from simply turning. The leaf is .012" thick. This is going to be fun.
I grabbed a piece of 7/32" thick 1095 and milled it a bit wider than the width of the original spring (including the locating tab).
Then the "eye" was drilled, in the mill, after locating the exact center.
The width is milled to within .010" of the finished size, leaving the locating tab "blank" standing.
The tab would be hand fit later.
The first side of the leaf is machined and the tool marks cleaned up by hand.
Given that the finished thickness of the leaf is .012", the question of how to hold the piece to remove the material from the second side arises. The answer? Soft solder.
The leaf is then machined to within .004" of final thickness. It's finished by hand to remove any tool marks because I want the spring to (a) last more than a week, and (b) look like it should look.
The rest of the spring is filed up by hand, polished and the tip of the leaf curled as original. Here it is next to the unbroken spring from the opposite lock.
The spring was hardened and tempered per the usual process, but with extreme care due to the fact that such a thin spring, after hardening, is apt to shatter just by looking at it too hard, to say nothing of dropping it or bending it in any way. After tempering, it was polished and the lock reassembled.
Here's a video showing the operation of the safety sear.
The barrels, by James Purdey himself.
The inletting is what you'd expect: perfection.
A couple shots of the assembled gun.