NHT3
Grandmaster
IMHO Absolutely NO lapping compound unless you want to end up with what the GIs used to call a "rack" 45.. Checking mags for possible problems is a good idea. I wouldn't do anything until I had 2 or 3 hundred rounds of factory hardball through it. That should be good enough to get it going.. Besides, 90% of the fun of having it is the practice.. You didn't mention what make it was?? Just curious