I added the matching comp and it will not function with my carry rounds.....or my other carry rounds - Faxon Firearms Match Series Straight Fluted Glock 48 9mm Luger Pistol Barrel

I did not see any tolerance or fitting issues and yes, you do have to remove the O-ring/ thread protector to get it into the slide. I got the Faxon EXOS-533 at the same time just figuring that as a pair, I would have the best chance to get the mod working.

My G48 has been 100% reliable using the Shield Magazine conversion for several years. It feeds everything. I cleaned this new barrel and installed the comp as instructed and let it sit overnight. Just to rotate it out, I fired my carry rounds (Gold Dot 124+P) that have been in the mags for almost a year. I had repeated failures to feed and did not get a single magazine to feed all 15 rounds. They would bind and index on the feed ramp. So I stopped, cleaned it, and then ran 50- 115g FMJ and 50-147g Federal Syntech and tried another mag of the good stuff. Better, but not 100%. Cleaned it again. Ran 30 more 115g and realized I had over 200 rounds fired at this point. I tried another mag of 124+P Gold Dots - no joy. I tried a mag of 147+P Win Rangers - no joy. I tried 124+P Win Rangers - No joy. Effectively, nothing I had with a hollow point would feed reliably and I had already doubled the cost of the barrel trying to find that out. Magazines of FMJ run like a champ so I don't think it is the magazines. Same mags, same rounds, with the factory barrel - zero issues.
So I am torn, when it went bang I did notice the comp effect but the "hot stuff" is supposed to make it work better not worse. It was only 100% reliable running FMJ. Fearing tolerance stacking as a result of the Shield Magazines I tracked down some of the new Glock 43x/48 metal bodies to see if that fixes it. That's another $100 so this whole exercise is a big fat - MEH.