The David Twigg lock is a very large lock. It would benefit from a hand forged new mainspring, to match the lock's mass. Years ago I built a half stalked fowling piece using one of them, and it that case, the lock functioned superbly, but it is the only one I've seen that did. I have a Davis Twigg lock in my lock drawer that was rebuilt by Bob Roller, and re-frizzened by Larry Mrock from the Mould and Gun Shop, but it is still a marginal sparker. I shall use it to re-build a flint Hawken that I built in the late 70's...a big rifle.
I have found from long experience that these frizzens range in performance from
poor to superb.The poor ones will be carbon deficient and the superb ones will be
hardened. The Twigg I saw at Friendship acouple of weeks ago was one of the 14
I made and it was a hot sparker.I did nothing to any of the frizzens and would have
rehardend them if they appeared to be substandard.The Shoults lock had frizzens
that were originally cast from 8620 which is fine for the plate and cock but no good
for frizzens and had to be case hardened again after about 100 shots.There were
others that did not have to be redone for whatever reason.A California shooter kept
a log book on one of these locks and recorded 15,000 shots and he asked me if I
could recondition it.I did that and fitted another frizzen as well. I have heard no more
from him and that was in 1987.
Bob Roller