That rifle is a beauty. Wow...
Barrels by Bill Large were legendary, and it is my understanding that the ones marked JJJJ were his top o'the line. Mr. Large had first class machinery, but he knew how to duplicate the work done by the old-time barrelmakers. His bores were generally tapered, just a couple of thousandths larger at the breech than the muzzle, effectively putting a small amount of choke in the bore.
I love that lock. I've handled a bunch of original 19th century military guns, including four or five over the past year, disassembling, carefully cleaning, and reassembling the locks. These 160-180 year old locks are still ready for service. The internal fit and finish, the quality of the springs and heat treatment, is all first-class.
I believe an old-time riflemaker would have very likely just ground the half-cock notch off the tumbler. Most people now consider this unsafe, but it was a very common practice years ago. Of the dozen or so 19th century sporting rifles with double-set triggers that my dad collected, only one had a fly. All of the others were finished without a half-cock. That may or may not be the case with this rifle, but it would not surprise me. I hope
@BigSkyRambler will let us know if a fly has been installed in this lock, or if the half-cock notch has been ground off. Lots of photos would be appreciated!
The hammer on this lock is clearly a replacement, and it is possible that the internal parts are replacements, too, retrofitted to this original lock plate. If that is the case, the tumbler may very well have a fly.
Bob Roller, a master builder of locks and triggers, knew Bill Large and a number of guns and rifles were built with Large barrels and Roller locks and triggers. Mr. Roller would have been quite capable of re-tooling the mechanism of this old New Haven lock. If he did, he may have placed his mark on the inner surface of the lock plate. On the other hand, that looks like a Siler hammer screw. I suppose Siler internals could have been fitted to the New Haven plate.
I think this rifle is outstanding in many ways. Thank you for showing it!
Notchy Bob