The gun I have them on is a 300Tomahawk. For those of you that are not familiar with the 300 Tomahawk it is a 300 RUM improved which is equal to the 30-378. Mine has a 10 twist which allows me to shoot 240 grain SMK's which has a lot more recoil than any 300 RUM. They do not slip or they would be in the garbage. To each his own.