.220 swift will be hard to find in factory ammo. .243 is a wal-mart calibure, it will be every where like the 30-06 is. if your going after yotes and want a cal. thats been designed for that then take a look at the ruger 204. 4225 fps from a 24" barrel. its as fast and flat shooting as its gona get I think. and its in factory ammo. so it shouldnt be hard to get a hold of.