I bet this could be used to get .223 subs to cycle:
http://gunbroker.com/Auction/ViewIte...Item=112532042
The bolt is in the rotated position, but its straight blowback. These are used for short range training ammo and maybe for simunition. You'd have to open up the bolt face to .223 dims.
The subs that I loaded and tested at one time ran about 16,000psi, doesn't mean yours will but its possible.
Jon