According to what I found in Pegler's book Powder & Ball Small arms---there are a few pages dedicated to a big pistol with English lock.It effectively is an fairly standard flintlock with the lockplate being rounded similar to a wheelock. But the frizzen and the pan work as a standard flintlock would. The lock exterior looks very different from standard more modern locks. The Cock and flint are very beefy, the frizzen spring looks familiar though the book says that the pan and frizzen were a one piece forging??? but there are other gee-gaws on the lock that are a mystery to me. I should imagine Master Robin might be more knowledgeable on this matter---however I thought I could share something from this book. :hmm: