It is rare for me to build a "cap" gun, but all of this assembly requires a little planning. Since the lock and barrel are already inlet, I would first measure where the front of the breech plug lies, and mark it. You could then indicate on the
barrel where the drum should be placed. I would then place the lock at the proper spot and see how this will work with
the spot where the drum will go. Hopefully, the barrel will be slightly forward of where it has to be, much easier to remove wood to move it back. If the barrel inlet is too far back, not sure, maybe accraglas, swear, etc. Assuming the
barrel and lock inlets are pretty close, I would then go ahead and inlet the barrel and tang, then the lock. It is much
easier to locate and drill and tap for the drum. I normally would remove the clean out screw in the end of the drum and
place it in the recess in the lock. Then insert a drill or some other pointed object that wil go down thru the hole in the
drum, and, holding the drum down in the lock cut-out for it, give it a tap to find the center on the barrel. You can then
drill and tap for the drum. Sorry, it took me almost as long to type this as it would to install the drum.....Don