.220 swift, 50g Vmax over 4064. 4100 fps of coyote grenade. I cannot remember a bullet exiting. They sure don't run away after being hit with one.

As as to the smaller caliber bullet- it makes complete sense. A 140 from a 7-08 does not go as fast nor does it have the ballistic coefficient of a 140g from a .260, which is the same parent case. You get a longer bullet and more pressure because you are pushing the same amount of lead down a smaller bore which in turn will give you more velocity.