You may want to look at defiance, I have a few, and run a .223 bolt as well as a standard bolt in one of them. It's a standard cut "non AIAW". I run a .260 Ackley and a .223 out if this platform, they both run on straight stack magazines. Bighorn also has a bolt head replacement for the .223 as well as others. A new bolt was $350 from defiance.