MPC

First of all don't get to attached to spec numbers as they are all over the place with different manufactures. What happens when the barrel hood to breech gap is large, as the gun is fired the bullets friction in the barrel rifling pushes the barrel forward and the rear of the round case forces the slide rearward which causes the two upper lugs to collide, so the larger the hood to breech gap the more movement between these two upon firing. This can affect accuracy if the gap gets too large but also another affect is the peening of the slides upper lugs with the barrels upper lugs which will cause the gap to grow more. Here's a simple way of looking at it, say you have a hammer and hold it above a surface then hit the surface, if the hammer is held 5 inches above or held 1 inch above which would cause more surface damage? .004 gap is not that much compared to the guns I see across my bench everyday. Usually after a lot of rounds are fired through higher pressured guns the barrels second upper lug will make contact with the slides second lug and any more peening Now bullseye guns need a narrower gap for extreme accuracy while game guns can and do have a little more clearance. MP Custom