I switched from my 223 to a 22 nosler. Factory loads are about 300 fps faster. I don't hand load, but those that do can get real close to 22-250 velocity. So this may be an option for you if you want to stay in the ar-15 platform. You may even have enough money left over to buy a 450 upper for deer hunting. That is what I do with my rock river 223. During deer season I put on the 450, coyote season back to the 223 for day hunting. (My nosler is my night rig) I got my 22 nosler from DTECH Uppers.
It is NOT a 243 though, but somewhere in between the 223 and a 243 as far as anchoring them. With a 243 you can hit them in the toenail and they go down! But if you hand load, you may get alot more out of the Nosler than factory ammo. Give the gentlemen at DTECH a call and they can help.
