normal speer .223 cal TNT bullets have a velocity limit of 3400. if you load them higher, speer says thay may come apart in air. If the box says made for 22-250 and 220 swift, im assuming it means its a special TNT that was made to have a higher threshold velocity. so a TNT made for a 22-250 may not be quite as explosive in a 223, just get the standard TNT bullets that have 3400 fps limit, it should say right on the box.