Well, I get a .5535 on a Berry's 124 grain hollow point and a .5527 on a Berry's 115 grain Round Nosed bullets using a micrometer. If I am reading my Lyman's info correctly I only find info on the 125 grain Hollow Point Jacketed with a C.O.L. of 1.075. I have no Flat Nosed bullets to measure, so I have asked Berry's what difference there is between the lengths of the two types of bullets. I would like to know as I am loading their bullets too, or as SHR970 says your gun might not like these bullets. So far all my guns like the Berry's bullets.