Aftermarket Barrel Details

[DM1906]

I have had good success "Fire-Lapping" rifles and revolvers to polish barrels and remedy "tight forcing cones".

Has anyone tried it on semi-auto pistols?

Auto-pistols work out very similar to rifles.  You do have to be very careful, though.  The throat/leade will lap out MUCH quicker than the rifling.  If you keep going until the rifling is satisfactory, it may polish the throat well beyond ideal or desirable.  I've found that the grit size affects the results more than any other variable.  More coarse grit primarily affects the throat, while more fine grit will affect the bore at a higher rate than the throat.  A delicate balance is hard to determine and is different from caliber to caliber (rifle), and I haven't lapped a pistol with the intent of polishing the bore (although it is a modest side effect).  Always use the softest lead/alloy you can, as it will allow the most expansion in the bore, but doesn't seem to make as much difference in the throat.  Don't worry about leading, just clean that up later.

Waiting for the bore to polish from normal firing can take a lifetime (they're designed to not wear with normal use).  By the time the bore is nicely polished, the rest of the gun may be completely used up.