Eric -- I have/use the TOTW tool that Ron mentioned, and it works great. Just make sure your drum is tightened snugly in the barrel before attaching the nipple-drilling/tapping guide. Put the barrel and lock into place in the stock, with the hammer on half-cock or full-cock to allow the drum room to seat into the stock inlet. Then ease the hammer down onto the drum, and mark a line on the end of the drum that coincides with the center of the hammer face. Remove the lock and barrel (with drum) from the stock, and clamp the barrel in a padded vise. Line up the tool (TOTW provides an instruction sheet) with your mark on the drum and tighten it into place with the allen wrench provided. Insert the drill bit bushing into the tool, and drill the hole (with a #29 bit, I believe; check this on the instruction sheet!) slowly and a bit at a time (cleaning out chips removed frequently) until the bit penetrates the "bore" of the drum. (You can usually feel when this happens, but you can also monitor progress by checking the depth of the drill bit with a depth gauge, or visually by shining a flashlight through the cleanout hole in the drum -- if it has one.) Remove the drill bit guide from the tool, but LEAVE THE TOOL ITSELF FIRMLY IN PLACE; DON'T LOOSEN THE ALLEN SCREW! Set up your tap and tap handle, and insert the tap into the hole where the drill bit and drill bit guide were previously. Tap the threads (use some thread-cutting oil) until the tap bottoms out on the bottom of the drum's center channel, and you're finished. Good luck! -- paulallen, tucson az