I had read with some interest that some members who had fired and cleaned their pistols had noticed darkening around the edges of the lands and grooves of their bores that did not seem to want to come out with normal cleaning.
One thing that I had done in the past was to use a product called "JB Bore Cleaner" to restore older rifle barrels that looked like they had seen better years. I had found in the past that this paste bore cleaner, which is intended to removed built up jacket fouling in a bore, has restored accuracy and seem to polish older rifle bores. It is not intended to nor will it remove pits. However it is an extremely fine abrasive paste compound and does obviously lap barrels when used.
Lapping a bore is the final stage used by barrel makers who use the hook cutter method, i.e. Obermeyer, Chanlyn, Koozer and others, to give a final polish to the bore to remove any roughness or tool marks prior to sending a blank out. In the case of both my own and my son's R9S's I did lap the bore with JB bore cleaner for about 10 minutes each prior to initial firing and did the same again after first range use. Based on the accuracy of these two I would say it worked.
To lap a barrel it is suggested that one uses a vise with leather padding around the barrel. I apply a liberal amount of paste to a Q tip and spread it inside the bore. I also apply paste to a large patch and using a rod with a jag tip, push the patch into the barrel. I put my finger over the muzzle end and that allows me to stop the patch before it exits the bore. I work it back and forth for about 5 minutes and then remove it, respread any paste that has accumulated at the edges and add a bit of oil to the patch. Then reinsert and polish briskly for another 5 minutes. Then done and clean all residue off and keep patching it till a patch comes out perfectly clean.
An alternative and more correct manner would be to insert an old rod with a jag from the chamber end and hold the barrel vertically in a vice. Using a patch around the rear of the jag to prevent anything from going by pour a small amount of molten lead into the barrel and allow it to cool forming a perfect lap on the end of the rod. When it has cooled hard, pull it out and coat it with the bore cleaner and lap as before. It will be a perfectly form lap to the lands and grooves and thus would be more efficient than a patch made lap. The heated lead won't hurt the barrel at all as a bullet fired would develop higher temperatures, but it will form perfectly to the lands and grooves.
It works and for anyone who has had accuracy problems or believes that the barrel is a bit rough, this method with remove the roughness, eliminate the dark edges of the lands and groove and will also enhance accuracy. The lead is soft and will not wear the barrel. It will only help the lapping compound get where it needs to be to enhance the lands and grooves.
