Re: Converting 222 to 223
Im not exactly sure where the holes are by your description. If "behind the bolt" is refering to somewhere on the rear bridge of the action, those holes should not cause any gas blowback. The holes "in front of the action" sound like they are drilled in the barrel. If those holes are drilled deep enough they could have entered the chamber/bore area and caused the leaking gases. Then a rebarrel would be needed.
A rebarrel would cost you around $200.00+ for the barrel. Then another $200.00+ for the gunsmith to chamber, cut threads, and crown. Reblueing would be $100.00+. Depending on what you want there could be some other costs. If you want to drill and tap for sights it would be around $25.00+ per hole. If the barrel has a non standard contour that you want matched it could cost another $100.00+.
One other thing you can check. Are you sure its a .222, could it be a .222 Mag? The way you describe the incedent, it sounds like a case failure.
Good luck, Tony