I loaded up some 10mm the other day and had a chance to chrono them yesterday. The results were confusing. 155gr Berry's HBRN plated CCI 300 primers 11.9 gr AA #7 1.250 OAL Glock 20 KKM standard length 10mm barrel OK, most of the rounds chrono'd in the low to mid 1300 fps range. However about 6 of the 50 rounds I chrono'd were well over 1600 fps, with 2 over 1700 fps. The highest velocity was 1766 fps. I've been loading for a couple of years and am no where near an expert....In fact I did over crimp these rounds. On several I had a stoppage due to a "ring of copper" left in the barrel due to over crimping and cutting into the copper plating. I can fix that next time by paying more attention to proper crimping techniques. But 1766 fps ??? My first inclination was to blame the chrono. Well that's like a pilot blaming instruments for readings that don't make sense. That can be a bad idea. Any thoughts on where I biffed this one up? I'm just another crazy New Mexican.