Had one that converted a .222 Rem to a .22 WMR. Accurate when it worked...but made of some light-weight metal which did not hold up very well. After <20 shells, the rim on the adapter peeled right off. The adapter also liked to stick in the chamber which made it a pain to eject both the adapter and the spent casings. I found a site which sold stainless adapters, which would, I assume, hold up better than the one I had. A nice idea which I have had bad luck with. I'm with KN...buy the additional barrel and make life a bit easier.