I have a P320C 9mm with a 250C threaded barrel. It sticks out about 1/4" farther than you would expect but otherwise works perfectly. I ordered it direct from Sigs online store. Tested with Compact and Sub-Compact frames. My can is a Silencerco Octane 45HD. My PoI shifted about 2 inches lower with the TB vs the stock barrel. Groups didn't change much. With the suppressor casings eject with plenty of authority. You cannot see the a-zone of an IDPA target at 25', but you can center the dots behind the can and center them in the targets silhouette. The extra muzzle weight from the can really helps keep the sights still. I noticed my groups tightened up a little as long as the target isnt completely blocked by the suppressor. Past 50' though, the dots weren't precise enough to get any groups to brag about. Speed shooting is interesting. The gun feels like it recoils at half speed with the can on. It feels like the slide has completely cycled before the muzzle has finished rising. The TB is threaded 13.5 x 1 LH. Unlike my 1/2 x 28 RH barrels, there is an oring so I can get through a whole magazine before re-tightening. I don't know why Sig says the barrel is not compatible. My guess is that since the barrel extends a full inch from the slide, this combined with a heavy suppressor could accelerate wear on the barrel or slide as it tilts during recoil. Probably no more than any other suppressed pistol though. My other guess is that the longer barrel requires you to insert it into the slides muzzle at a steeper angle and if you do so carelessly, you could damage the threads. There is about 5/16" of smooth barrel between the slide and threads so Sig might be working on shortening it. Anyways, I've put about 400 suppressed rounds downrange and haven't noticed anything abnormal.