Lapping loading taps

[dvd]

It would be tricky but just about do-able. You would need to be able to confine the elecrolysis bath to a small volume that encompasses just the tap recess area and not the rest of the gun, otherwise you would need a huge bath to accommodate everything. You would then need to protect the areas where you do not want build up with an easily removable coating. I have used a solution of common or garden polystyrene foam in acetone as a suitable lacquer for protecting areas during hot salt bluing or electroetching. Completely untouched by strong chemicals and a perfect insulator, but comes off straightaway with an acetone rinse. You could plug the barrel lead-in bore with a plug of polystyrene foam.

I visualise lying the gun on its side with the tap recess vertical, sealing the across bottom of the recess with tape/lacquer/wax, in fact anythng that makes it water tight. The upper end of the recess would be fitted with some plastic tubing pointing vertically, sealed in place again with anything that gives a watertight seal. The net result is a narrow vertical tube that can be filled with the electrolyte, the bottom few cm of the tube being the tap bore itself. For the electrolyte you can use a solution of ammonium ferrous sulphate (cheap, off Fleabay) in water (17.5 grams in 50ml water), acidified with whatever acid you can find to a pH around 3-4. Wire the barrel to the negative terminal of a battery. Insert a large iron nail into the upper part of the tube with this wired to the positive battery terminal. The battery should provide only about half to 1 volt - you don't want to see much bubbling from the tap recess. Significant build up of iron on the exposed metal area should occur in an hour or two. In my experience with threads, the coating feels gritty at first, but it wire brushes readily to a smooth finish.

Obviously you would need to do some experimenting first with bits of scrap metal before commiting the gun itself to the process, but at least when building something up it is easy to reverse if things don't work out - unlike processes that remove material!

Thanks for your very informative reply.
Never thought about the combination of polystyrene and acetone.
Devising a leak-proof system of how to keep the electrolyte within the tap bore is challenging, but It sounds doable.

[bill57]

Thanks for the replies guys, all pretty much as I expected. No shortcuts to this, so I will continue to avoid taper taps until I have some (if any) expertise in this.