I met a guy, that replaced barrel in his MR223A1 (non-CL) after 25K rounds, because its accuracy deteriorated significantly. Barrel costed him around 3000zł (inlcuding 23% VAT), that was roughly 700-750 EUR back then. With CL barrel in MR223 you can expect twice as much. In case HK is not around anymore or whatever, good gunsmith can take barrel blank, chamber it, fit receiver extension removed from old barrel, profile it and drill gas port. It is not something not feasible to do. In case of bolt problems, you can use regular AR15 bolt in HK (OTB feature will no longer work with "regular" bolt). No need of new rifle when barrel is shot out.