Looks like an old Northstar, or possibly a Green River Forge, gun to me. The Lott lock went through many different manufacturers over the years. As far as I know they were always made in Italy, but by several different companies over the years. They almost always had a weak mainspring. This can usually be remedied by heating and retempering. The frizzen is another issue. They are almost always cast mild steel, that is case hardened. Once you wear through the case, its over, until you either reharden it or half sole it. The geometry in these locks can run the gamut from pretty good, to horrible.
After all this bad news, I have to say I own four of these locks, and have become pretty good at making them perform.
Green River Forge regularly made new mainsprings when they used these locks, so if it has the old spring in it it is most likely one of Curly's.
Hungry Horse
