Guys - I read an interesting article in an old book I have about lapping your ML barrel or more specific, how to make a lapping plug and thought I would pass it along.
To make a plug, put two or threedamp patches about 4" down the muzzle and insert a clean brass brush into the bore leaving the threaded end exposedthenpour molten lead carefully around the brush. Be sure the lead is hot enough to flow down to the opposite end of the brush and to be around the entire circumference. Once the lead solidifies, screw the ramrod onto the brush and pull it out. Trim any excess off the end and remove the patches.
To lap the bore, appply polishing compound like JB to the plug and work it back and forthe through the barrel.
I tried it with an old T/C .45 barrel I have and it works pretty good. And if you're concerned about the excesslead, it does not stick to the steel barrel and just falls out or comes out when you remove the patches.