I am looking to honcho a group buy for a 30 cal Mihec mold. It is a gas check design and buyers want 2 different diameters. 316 and 311. Since the mold makers use a shaped end mill to interpolate the cavity, the gas shank diameter will vary by 5 thou as well. If target the 316 version to have a 0.283" diameter gas check shank, will 0.278" be too small for the 311 version?