Lapping can pretty much be done anywhere that a tight, smooth fit is desired. My Kimber 5" gun came with a rough slide to frame fit -- the slide wouldn't track of it's own weight. By lapping with JB Bore Cleaning cpd, a very fine abrasive, it smoothed to allow a smooth fit without loosening the tolerances much. Most factory guns can stand a little lapping of something or another, but you hear about it more on custom slide/frame fitting b/c it's necessary to achieve that final fit.