Had a Remington Mohawk 600 with a 1/12 that would shoot the Sierra 63 grain SMP into .5 MOA with 26.0 grains of 748. Also have a Valmet 412 12/.223 that shoots under and inch with that same load.
Sold the Mohawk to my friend in Texas as I knew it would get more use and his family have already killed several deer with it and the Sierra load.
Only .223 bolt gun I have right now is a 1/8 Tikka that I got from Mackay Sagebrush. With 75 grain Hornady or 63 grain SMPs it will run in the .5 area...
Bob