Hi Art and Headroom,
In the old days, a lot of the better barrels were lapped at the factory. Today, they don't bother because modern manufacturing processes produce better barrels than the old guys made, even with lapping.
Lapping won't hurt to a point, but it is, after all, speeded up wear. As in stoning an action or trigger, it is creating wear in a few minutes that would take years of working the action. But that still means less useful life. Like most of life, it is a tradeoff. And lapping will not make a bad barrel into a winner. I might make it an even worse barrel.
Jim