If you mean upgrading from a smooth twist to a smooth twist x barrel yea that should be possible. Considering both are just liners it should be a simple swap. Although I think you would have to modify the streamline shroud to some degree in order to fit the upgraded barrel. If your thinking about making an upgrade you could even skip the smooth twist x liner and go to the newest smooth twist superior liner. That way you could shoot slugs and pellets out the same barrel. Although if you go this route you might want to add a dreamline power plenum so that you can shoot the slugs at the optimal 850-880 range. Otherwise you would probably be limited to lighter slugs.
Heres a really good video showing how to take apart a smooth twist x barrel. The process should be the same for the basic smooth twist system.
https://m.youtube.com/watch?v=7ZqWIEyOijY
