What size roll pin punch are you folks using to drift out the "locking block coil pin" that holds the sear block? I have "roll pin" punches, and the #4-1/8" pin looks to be the closest size, but it seems to be a might tight in the pin hole in the frame. The # 3 is way too small and the #5 way too big. And what the heck is a "coil pin"? I am "assuming" it's just another name for "roll pin", yes? The parts diagram shows both front and rear "locking block coil pins" as the same, but the front pin whole in the frame is just a tad larget diameter. Thanks for the help. I'm loving my M&P40!