I have owned 3 of Hamm's Gonter locks. Built a rifle around one back in the early 70s. Was supposed to be one of the best locks you could get then but I was never impressed with it. Years later I replaced the lock with another one, probably after Mitton had taken over. It wasn't much better. Recently I bought a flint pistol that had been built in the 70s with the same lock and it works fairly well but I still don't consider it a high quality lock, at least not by today's standards. I also had one of the radio-active frizzen plates I put on a different gun. Sparked great.
Based on my experience, I wouldn't build a gun around a Hamm lock given the choices available today.