I think Diggory; if he's reading this, ought to consider a book devoted to hammer guns similar to his work on box locks. Thankfully, on this side of the pond there are still plenty about at prices that would seem quite moderate to many on this forum. Ones to maybe look at are those made for live pigeon shooting as they often have 2 3/4" chambers and are good all rounders. Hammer guns were made well up to the second world war here so good steel barrelled nitro proof ones with 2 3/4" chambers can be found. Good luck in your search. You will be quite taken with their graceful lines. Lagopus.....