I think you've done a nice job on your rifle too. The wood has some very interesting character especially in the butt, and it looks like a great shooter.
Regarding your lock...I too have used Davis' big Twigg lock, and unless everything is perfectly balanced, hardened and tempered, no sparks will issue. You have done a great job on the mainspring, though I'd like to see a little more metal right at the bend. Nice job filing out the finial.
I used one of these in a fowler many years ago, and it sparked like crazy. The one in my parts box right now, will not spark at all. But it was a kit or parts set, and I assembled it myself, so I have lots more work to do. But look at it this way...think of the satisfaction and what you've learned about locks in the doing. That's pretty hard to put a $ figure on, eh?
Seeing your rifle, I just might use my Twigg lock in my next build, which is also an iron mounted Southern Mountain rifle. I've been saving it for a blunderbuss....
