Above two images a Davis lock modified for a Tulle by David Rase.
This lock is for a bench copy Nicholas Hawk rifle. It's entirely from the Chambers late Ketland. It's been made considerably smaller with a modified plate and pan, hammer and screw, and frizzen spring. The original lock has a replaced hammer and frizzen, and frizzen spring. The plate, marked BOULTON, is original as are the internals. Most Hawks that I've seen have rollers on the frizzen spring.
This was made in 1989 and I freely admit if the Chambers early Ketland would have been around, I wouldn't have bothered. The plate was milled from a solid hunk and filed up. The hammer and frizzen came from Reeves Goering. The frizzen spring from the Davis Twigg. The internals from a large Siler and the long mainspring forged from a piece of spring steel I found at Dixons. Talk about a conglomeration!
Above three images supplied by Bill Shipman.