Took the XP-100 out for sighting in and chronographing the first loads. First one out of the tube surprised me at 3066 fps. with a load of 15.5 grains of 2400. Averaged 8 shots at 3030 fps. I was amazed since it's only a 10 3/4" barrel. For ha ha's I broke out the 14" Contender in .222 since that's the only other comparable cartridge/ barrel length I have. Only averaged 2896 fps. I have decided the .221 Fireball is a screamer. Tried some loads with Reloader 10X but I don't think it's quite fast enough from the short barrel. Only averaged about 2563 fps. Good accuracy though. Not terribly excited about the groups but not disappointed either since this was just a random load, no development done yet. Definitely minute of woodchuck.