Personally, I wouldn't do it for two reasons...

1. You'll ruin the value of the gun. The 24V's in .222 Rem are one of the more desirable ones, and in good shape will bring upwards of $500. Rechamber it and you'd be lucky to get $350-400 out of it.

2. Not sure if I'd trust that thin-walled pencil barrel with the 223. If you look at the newer Model 24's that were offered in .223, the barrel diameter was noticeably thicker.