The Hornady 10th edition load book recommends a COL of 2.245 for a 120 gr AMAX, 6.5 Grendel. So, in theory, if I load this cartridge to book at COL 2.245", either the bolt won't close, or it'll perform final seating with a jump of 0". Or maybe something else I don't know about, yet. The other side is maybe I measured something wrong, or I assembled the barrel to the upper receiver wrong. Empirically the rifle experienced a remarkable number of jams with the factory 123 AMAX rounds, stovepipes in all cases. Granted this barrel came with an adjustable gas block which I used SOP to adjust but, this isn't my first adjustable gas block rodeo. And, I was using metal 7.62x39 magazines. I mention these factors in order to paint a more complete picture of the experience. I'm mostly concerned about the apparent shortness of the chamber if in fact that is the case. Thoughts on the matter greatly appreciated.