Did some measuring today in preparation of cutting. First of I measured the barrel using a rod inserted in the barrel with the barrel placed in the upper witg the BCG. Barrel-length turned out right at 16”. Measuring of that when I mark it down for 12,5” the distance between the gas port and the would-be muzzle is 2,75”. I thought the gas port on a middy was at 9” thus equaling a distance of 3,5” between gas port and the muzzle of a 12,5. Is this a potential problem? When measuring the distance from bore to gas port it shows 9,5”.