I have a P320 subcompact (3.6" barrel). I hate the grip. I could get an XCOMPACT grip module that might be better, but I'd rather convert to a Carry or Full-size grip if possible. Would it work to change to a threaded barrel, add an Armory Craft compensator (https://www.armorycraft.com/product-page/sig-sauer-compensators-p320-p226-228-229) to extend the slide, and then use a Carry or Full-size grip module? If so, would a 3.6" threaded barrel stick out enough to mount the AC compensator?

I have a carry grip module that I cut the front portion of the rail/dustcover off of to make it fit the subcompact slide. Looks good and works fine.

Armory Craft lists that compensator kit for a compact, full size or X5 length slide. I would verify with them if it's going to work with your subcompact slide before committing any money to the project.

You might take a look at Wilson Combat grips.

Their X-Compact grip matches the SC slide with a Compact-size (15-round) grip:
https://wilsoncombat.com/grip-...cp320-x-compact.html

Their Carry II matches the SC slide with a Full/Carry-size (17-round) grip:
https://wilsoncombat.com/grip-...wcp320-carry-ii.html