I'm thinking about getting the X carry grip module for my 320 compact 9mm but not sure what magazine will fit the X carry module, can someone share what magazines I can buy thanks.

The most recent iteration of the 17 round magazine will fit the X-Carry grip module. These are denoted by a different baseplate, with a square retainer and a circular SIG logo.
The older 17 round magazines, with a round retainer and a Sig Sauer logo, will not fit in the X-Carry grip.

The new and old version of the magazine have the same part number, so if you're ordering online, you'll want to specify with the retailer whether they're the new version or the old version.

Here's a comparison photo. New baseplate on top. Old baseplate on bottom.




If you have some existing 17 round magazine with the older baseplates, you can modify the baseplates by cutting/grinding off the "ears" that stick up. That will allow them to work with the X-Series grip modules.



Otherwise, you'll have to replace the old baseplates with compatible baseplates. Sig has a baseplate replacement kit, part number KIT-MOD-MAG-FLR-PLT-BLK / UPC 798681591862, but they're in very short supply. There are some aftermarket replacement baseplates that are compatible with the X-series grip modules, like the Springer Precision 0.25" basepads. Here's a shot of my P320 with X-Carry grip module, using one of my older magazines with Springer Precision basepad installed.

Similarly, the 21 round magazine baseplates have been modified as well.

The old version has a larger round SIG logo with sunken lettering, a round retainer, and a taller textured portion on the sides of the extension. It is not compatible with the X-Series grip modules.




Only the newest version, with half-height texturing on the side of the extension, square retainer, and smaller round SIG logo with raised letters, will work with the X-Series grip modules.



17 round magazine > Old 21 round magazine > New 21 round magazine:

Thanks for the replies.

Yep, ran into that myself. I bought the X-Carry grip module for my P320 Carry in .357sig. Magazines that came with the gun had the "old" base plate. SIG does not sell .357sig mags with base plates that fit the X-Carry, so I had to improvise with base plates from GGI and retainer plates from Obsidian firearms.

I did the same thing w/ some of the GGI Hard-Duty Base Pads and the Obsidian Arms Retainer Plates when I got the X-Carry Grip Module, but I considered it more of an upgrade....

Seriously, it's a REALLY Nice solution in my opinion!