Threaded barrel to replace oem 3.1 barrel - Faxon Firearms SIG Sauer P365 Threaded Barrel

The threaded barrel that's supposed to fit as a replacement for the 3.1" barrel doesn't. It will run, but will beat itself up against the slide. The "chamber section" is oversized causing deformations on the barrel. Faxon sent me a replacement, but it's exactly the same size. I can't imagine this isn't a known issue. They offered to give me a credit, but what's the point if their barrel doesn't fit? I'm going to get creative with the Dremel and see if I can make it work. Fingers crossed.