In a quality built rifle there will be no difference in the accuracy potential of these two rounds.
Personally, I prefer the 22-250. It will do anything the .223 will do and more. It is also much better at launching the heavy bullets (69gr-80gr) than the .223.
However, seeing that you do not load, you would be better served with a .223 where there is an abundance of factory ammo including a lot of discounted military ammo. This would provide much more trigger time at a reasonable rate. The other advantage of the .223 is longer barrel life.
As to the 7 twist - I would much rather have a 9" twist which would shoot everything from the 50gr bullets (or lighter) on up to the 75gr bullets. If you intend to limit your shooting to 40-55gr bullets than any 12" would work fine
Last edited by Varmint Hunter; 01-04-2008 at 01:39 PM.