Question on M&P Pistol barrels

[45caliber]

I have two M&P pistols, a sub-compact and a Pro Model. On both of these guns I have noticed some deposits on the lands and grooves which are very hard to remove. I can physically scrape some of it off, but no cleaner or copper brush seems to remove it. Any ideas about what these deposits are and how to remove them? Thank you.

 

[WR Moore]

You're probably looking at lead deposits from lead or plated lead bullets. Bownells sells the Lewis Lead Remover to deal with this problem.

If you haven't-to your knowledge-shot lead/plated lead bullets, try putting a cork in one end of the barrel and filling it with Hoppes. Let stand for several hours and patch out. Several brands of frangible rounds (powdered copper slug) leave a noticable deposit, but these can generally be easily removed with the various copper solvents. BTW-use nylon brushes with the more active copper solvents, otherwise you destroy your brushes while you're trying to remove the copper.