The 223 can be re-chambered to 22-250. The bolt face will have to be changed to a .473" bolt face but this is inexpensive, and the magazine body and follower will need to be changed to a 22-250 magazine, the 308 mag may or may not feed properly, they are different. If you choose to sell your 223 and buy a 308 to convert, you can sell the barrel or trade if for a 22-250 barrel but the mag may still be an issue. The 22-250 with a 1 in 8" twist with 75 grn A-max's is an excellent long range cartridge, but for shorter ranges the 1 in 12" or 1 in 14" will give a little higher velocity and handle the light (40 grn to 55 grn) a little better. A 1 in 12" twist barrel would be easier to find, however you 223 barrel is probably already a 1 in 9" or 1 in 8". One thing to consider before starting the project, the 223 is just as good for shorter range work as the 22-250 if not better. The trajectory out to 300yrds is not going to be noticeably different in the field, and the barrel life of the 223 is much better. The 22-250 will also heat the barrel up much, much faster and require more cool down time. As a prarie dog hunter this is really important, because if you get that barrel too hot is wont last long at all. The 22-250 will get too hot to touch in very few rounds. Another option if you want flatter shooting round is the 204 Ruger or one of the 20 caliber 223 wildcats, they are as flat shooting as the 22-250 but much more efficient.