I'm bore slugging a barrel for a gentleman. M70 stw. First 4-5 inches past chamber tight and then loose to muzzle. I dont see any significant erosion or cracking. I normally hand lap the tight spots but this is a whole area and at the beginning of the bore after the chamber. Could the bore be too big the entire length after the tight area? Can I "bump up" the lead slug farther down the bore and mic the slug to measure the bore?