Merry Christmas
I have a FS 9 and 9 compact M&P. If you put the 2 side by side with magazines there is very little difference in size. The compact is obviously supposed to be smaller and easier to cc. Not much to me. I am wondering if I might as well car the FS.
Or get something single stack that would be a noticeable difference in physical comfort but lack the extra ammo.
Any thoughts?

by the way I have been using and inside the pant holster.

The compact has a shorter grip and a shorter barrel and slide, but is otherwise identical to the FS. In fact, the FS slide and barrel will fit and function perfectly on the compact frame, as will the FS magazines.

If you want something thinner, then the M&P Shield is one possible answer.

For me the Compact is much much easier to carry. The FS with the full compliment of 18 rounds tends to get a little heavy. The toughest part of a handgun to conceal is the grip (In my opinion) espically if you carry IWB.
Have you given any thought to a "chop job" on your full size? Basically you have a gun smith cut the grip of the full size making it able to accept the 12 round magazine (and the 17). Now you have a full length slide/barrel for added accuracy, velocity, less recoil, quicker follow up shot. And the concealibility of a compact grip. Search this forum and you should be able to find one of my threads with pictures of my chopped M&P's.
just a thought
1SG

this is not 100% true. It will prob fit but as far as function it may not work. The compact is exactly that COMPACT the full size is a full size, when the full size slide is attached to the compact frame there will be a gap where the slide meets the frame exposing the recoil spring.
i would NOT try this
1SG
Out

Single stacks are too small for me. The M&Pc has a grip that's too short, for me. For me the perfect combo is the G19. So I guess if i were in your shoes I would pick the FS

Sent from my SCH-I545 using Tapatalk

Well, I had to try it. I put the FS 9 slide on my 9C. Dry fires and manually cycles with snap caps just fine. As MP1SG says, the dust cover on the 9C frame is shorter and exposes the recoil spring.

I also put the 9C slide on my FS frame. No Go. I can't rack the slide back far enough lock the slide and flip the takedown. I didn't bother to see what was hitting.

I would not use either of these configurations. (Although I did try them at home).

I don't believe I would get into the "chop job" thing. I would just buy another that was designed and built just for what I want.
There is always the chance that I need to try other holsters. I am fairly new to this.
as always I am grateful for all the help.

I was not suggesting that a pistol be used in this configuration (although I know of people who do. It was primarily a statement of the size of the frames being identical - hence little difference between the FS and compact.
I was not suggesting that a pistol be used in this configuration (although I know of people who do. It was primarily a statement of the size of the frames being identical - hence little difference between the FS and compact.

As you have found, the compact slide will NOT function on the full-size frame.