I'm sorry, did you just say you wanted a KelTec SUB-2000?  

I bought the FPC specifically for M&P mag compatibility. It looks like the Gen 3 Sub2k only has Glock compatibility right now.

Thanks

Correct, but the Gen 2 MultiMag SUB-2000 is still available, comes out of the box w/ the M&P mag catch, and you can adjust the LOP.

Can't fold the Gen 2 with an optic.

ETA: *out of the box.

You can.  You have to mount it forward and it won't fold all the way.  It'll still fit in a sling bag.  Or you can mount a Red Lion rotating forend.  The S&W is a good gun, just limited on mag brands to one & as you discovered, can't adjust the LOP.

Is the factory stock adjustable?

If not, are there any aftermarket companies that are making adjustable stocks for these?

Negative on the adjustable factory stock. See the Taccom link above for adjustable aftermarket stock.

Just got my own FPC.

The reasons I prefer the FPC over the Sub2000:

1. Folds completely with an optic on top.
2. Doesn’t come with sights but the built in hump on the receiver raises the pic rail 1/2” higher than on the Sub. I even added aftermarket sights to the Sub and still had a hard time getting behind the sights.
3. Better trigger. No need for aftermarket.
4. Softer recoil. When my cheek was on the tube of the Sub, it felt like getting punched every time I pulled the trigger.
The FPC stock design probably helps with this.
5. Better, easier to use charging handle.

It seemed like some of these issues could have been resolved with aftermarket parts, but I feel like they should have been fixed at the factory.
(I’d love to know how many Sub2000 owners who are talking about the FPC being more expensive have spent hundreds more in upgrades to get their gun where they want it.)

I bought the Sub2000 because I have extended Glock mags and was excited to finally have a “Glock carbine”, but the above issues caused me to sell it pretty quickly.

We have a full size and a compact M&P, so the FPC does give me mag compatibility, and it fits easily in my cheap computer backpack.

Only one range trip so far but it ran a variety of ammo perfectly.
Several one hole groups from 25 yards.

I added a screw on trilug mount from Angstat Arms and found minimal POI shift with my R9 suppressor mounted.

On top of all that, it just feels like a quality firearm.

This was definitely one of the most satisfying new gun range trips I’ve ever had.

The brand new Gen 3 SUB fixes the optic & sight issues, as there are no factory sights & the optic rail rotates 90 degrees on folding.

I was dumb and ordered the Angstadt Arms tri lug brake.  The shims are bigger than the barrel, so they stick out looking funny and are sharper than the devil too.

If i ordered the tri lug flash hider or the plain tri lug mount I would be done now

Any idea where to get smaller OD shims?  my amateur instinct is to mount them on a bolt as an arbor, then spin them with a hand drill against some sandpaper to reduce the OD.

Sorry, I just tightened mine with some red Loctite.
Maybe not a long term solution, but I probably won’t shoot it much with a suppressor.

147 grain rounds through my YHM R9 were pretty loud.

Will anything stay subsonic in a 16” barrel?

I've had good luck w/ 147 grn Winchester white box hollowpoints from my Gen 2 Sub.  Gold Dots might be a little slower based on testing w/ my Glock 26.

I figured I wouldn't shoot this a lot suppressed either, so I went with the brake instead of the plain tri lug.  It does look more keen than the thread protector for sure.

It took a long time, but a file and sandpaper reduced the diameter of the thick shim, and the thin shims could be cut with scissors.

http://www.ballisticsbytheinch.com/9luger.html  indicates that for 147 gr Federal hydra-shok loads the velocity increase flattens out after about 8"-12" of barrel.  Unfortunately, the peak velocity they measured is 1090 fps, just above the speed of sound from sub freezing to comfortable temperatures.

Remington makes a subsonic 9mm 147gr, which they say is 945 fps (out of what barrel they don't say).  147 gr Federal hydra-shok is said to be 1000 fps (4" barrel), but ballistics by the inch measured 951 fps.  Maybe loads advertised as subsonic are just enough underpowered to make a difference, especially at lower temps.  I haven't yet shot suppressed from a long barrel, but 8" has been subsonic with whatever 147gr load I've tried (and supersonic with 124 or lighter).

There are also 158gr and 165gr 9mm loads, I imagine those would be subsonic in any barrel.
--> https://www.freedommunitions.com/9mm-luger-165-gr-rn-hush-new.html

Guess I have a good excuse to go shooting!

Had to file the handguard a little bit but my direct thread AB Sabre fits right on.

After doing a little shooting, Federal AE9FP (147 gr. flat point) is subsonic at 75 deg out of a 16" FPC.

The Angstadt tri-lug brake worked great w/o a suppressor, but I had some diagonal stringing suppressed.  Not sure yet which part/parts to blame that on.

FPC -> home modified shims -> Angstadt tri lug brake -> Resilient titanium tri lug hub -> Griffin Bushwhacker 36.

The Bushwhacker seems to work fine on an AP5.  I'm guessing the lugs/brake ports don't agree with the suppressor.  I didn't find any baffle strikes.

I think I may try it direct threaded on the FPC next range trip, and verify that it doesn't do the same thing on the AP5.