I don’t think you can. if you have a 25 caliber barrel you can only add other 25 liners you need to get the complete set outer barrel,moderator , pellet probe and magazine when changing calibers. There should be interchangeablity between the Crown and Impact but the pellet probes are different as well as the magazines. Currently I have a 25 Crown and a 30 Impact in the future I will probably get what’s needed to use my 25 Crown x barrel in my Impact. But I’m going to wait a bit longer as I don’t think that the dealers have all the facts yet from FX and hopefully it won’t be a long wait for the components