Bunduki,my recommendation is to send the rifle back to Krieghoff, for the barrels! It is not likely that a finished barrel set can be fitted to your rifle easily. It is far better to start with an unfitted barrel set, at the K-gun factory! The process will be expensive no matter which way you go, but the chance of a screw-up is far less, and less expensive in the long run to have this done by Krieghoff, IMO!