I realize this is an old thread but it seems to be a timeless topic so here is some more pertinent information. I’ve been shooting Bear Creek moly-coated bullets through my G17. They are supposed to have a BHN of 12. I load the 135gr RN over 4.0gr of Unique with Federal SP and I get 967fps average velocity over my Oehler 35P with a SD of 10.6 (and a PF of 130.5).
I’ve probably shot 5,000 rounds of this load, interspersed with Berry’s and Xtreme plated bullet loads. I clean the bore more often than I do my conventionally rifled barrels (maybe every ~ 300 rounds) and have experienced no problems but I was noticing lead building up in the low spots in the bore. The high points of the rifling always seemed to come clean with conventional bore cleaning methods. I decided to pull out my old Outers Foul Out electronic bore cleaner and give it a try, but first I cleaned it the best I could with conventional cleaning methods (no Chore Boys, just bronze brushes, patches, bore cleaner, including JB, and a lot of elbow grease). When I used the Foul Out after that I was shocked by the amount of lead that was removed. It took five rounds of electronic cleaning to get to where no additional lead was being “plated” onto the cleaning rod.
For those not familiar the Foul Out uses a reverse electroplating process to strip the lead (or copper) from the bore and deposit it onto the electrode (rod) that is centered in the bore by means of tiny O-rings. As the lead builds up on the rod the effectiveness of the process decreases, evidenced by a series of lights, to the point where you have to remove the rod, clean off all the lead and start over again. Most of my experience with this tool has been cleaning copper gilding metal from the bores of my bolt guns but I have also used it to clean lead from my revolvers. I have never had to do five repeat processes to clean a bore.
I’m not saying I’ve quit shooting moly-coated bullets through polygonal rifled bores but I will continue to clean them more often and watch the lead build up carefully. For my new G34 I’m going to get an aftermarket barrel with conventional rifling and not worry about it.