Can tell you how they are put in...but it's a hard fix if you ever get one loose as the wedge slot has to line up with the barrel.
Are normally thightly threaded and then pinned...not cross pinned, but pinned from the rear. IF you cock the gun and lookd into the hammer recess, will see the miss-match of steel whee the end of the base pin comes through. That end is ususally kind of peened looking...some guns have a pin that is driven in that crosses the threads...others look like they are just peened (but suspect there was a pin in there). Pins seem to be made soft so that they will deform, letting them peen over and fill the hole tightly.
Basically, the peening and pin cross the threads, locking the tightly screwed in center pin in place. IF yours is loose, am betting that it's streached rather than coming unscrewed.
HAve had to do the center pin fix on an old brass framed revovler...if that center pin had anything but threading holding it in, I couldn't detect it. On that one, fitted the pin exactly were it needed to be, marked it, took it apart again, cleaned it and tinned it with lo-temp silver solder, put it back together and heated until the solder liquified. Fix lasted, but I'd not want to do the job a again.
On thing NOT to do, do not drive that wedge like you are pounding tent stakes. Once it pulls the barrel cylinder gap closed, any more force is just streaching the center pin/wedge slot.
Try a temp. "fix" of the wedge...just cut a thin shim of metal, glue it to the side of the wedge, and see if that fixes your problem. IF it does, then either an over sized wedge or welding and reshaping the current wedge may pull it all tight again. Do have one wedge still in service taht was tightened by soldering steel shims to the sides...if I wear it out, will weld it and reshape it, but it seems that a silver soldered shim works just as well as anything else.
