So I recently purchased a .357Sig compact conversion kit for my P320. I have a P320 subcompact in 9mm that I bought a number of years ago which shoots wonderfully and which I absolutely love.

However, when I pulled the FCU out to use in my P320 compact kit, I have found that it doesn’t fit. The notch for the slide release on the grip doesn’t match the location on the FCU.

My questions are:

Are there different FCU’s? How do I know which one will fit my new kit? Could I use one from an X Compact or one of the new FCU’s from the custom shop?

Thanks in advance for your help!

There has been a change in the P320 slide release. You will need the newer slide release. I believe the Sig part number is 1300891R.

Thanks for your response.

So to be clear, all FCU’s are compatible and essentially the same, but they are using two different slide release parts?

In 2016, Sig made a change to the 320/250 grip module that also necessitated a change to the slide release. For a while, the new style release was shipped with the newer grip as a package. I dont think Sig ships them together any more. I dont think the the slide release is considered a part of the FCU. A call to Sig to confirm part numbers will get you what you need.