Hi there. That is a 10 bore doglock musket built by about the best muzzle loader gunsmith in the UK. It has a 46” barrel. It shoots well and balances nicely. As to where you might get one, I don’t honestly know, as most of the guys works are one offs. I believe you can get a dog lock musket from one of the Indian gun importers, but I’ve never had one, so don’t know what they’re like.