I loaded some 10 mm ammo today and had made a change to AA #9 powder to get a little snappier load. As reference, I'm using Hdy 155 gr. XTP bullets. Ultimately I loaded 15.5 gr of powder (max according to the powder mfg is 15.9 gr), COL of 1.25". At the range, the new loads clocked a mean of 1195 fps. I shot 10 rounds, using the club's chrono that I've used for all my previous samples. The round should have clocked around 1370 fps and previous loads with a different powder are in that range (actually, the last sample had a mean of 1320 fps). I suppose the answer is that I shouldn't have changed powder but trying something different hoping to improve is part of why we load our own. Your comments are all welcome.