Something you should know. You don't need a rifle chambered in these calibers, if you're only planning on using the action. To build a .22-250, all you need is a Rem 700 short action with the .308 family boltface......243, .260, 7mm-08, .308, etc. If you want to build a .204 Ruger, get a short action with the .223 family bolt face.

Admittedly, the short action "donors" are usually harder to find than the long actions. Gun shows and the on-line classified sections of many shooting forums are a great place to look for actions and "donor" rifles.




As others have already mentioned, your accuracy expectations are a bit unrealistic. One-inch groups at 500 yards is a very tall order.

If you're thinking of shooting a .22 caliber bullet at those distances, you'd be well served by choosing a bullet with a high ballistic coefficient. The 75gr A-Max and heavier Sierra Match Kings are made for this kind of shooting, and you'll need a fast-twist (1-8" or faster) barrel to properly stabilize them.