Yes, that would work too. What I was saying is you should be able to just pull the bolt out and look in the slot that the bolt pin goes into. The hammers are made of different metals and have a distinctly different color as well as slightly different shape. That way you don't even need to remove the cartridge.
As you can see, the robtown (top) is noticeably lighter and a bit duller in appearance, as well as a little shorter.