Re: 6MM/22-250
All the above mentioned 6mm cartridges are roughly based on the .22-250 case. The AI more capacity, sharper shoulder, little rougher feed. The XC is a smoothed and shoulder-forward AI from the brain of David Tubb. The International trades a little case capacity for a longer neck. They will all get you to within a couple of hundred FPS of a .243 Win. with a longer barrel life. If you want more speed, go .243, don't go nuts trying to hot-rod a .22-250 size case. Look at the barrel twist if you want to shoot the heavy (105gr +) bullets to buck the wind.