Been tempted lately to pick up the new M&P Sport II but my last .223 carbine usually sat in the safe on range day simply because I prefer the longer site radius and feel of the standard 21" barrel USGI version for outdoor plinking .....
FF to what has kept me up at night lately... that is if S&W would offer their AR carbine chambered in 9mm at the current market price of under $600 not only would I buy one in an instant..... my guess is Im not alone in that thought.
A 9mm AR Carbine makes alot of sense to me for several reasons :
Slightly cheaper ammo that is common with handguns, more sensible for home defense with more bullet mass that has lower wall penetration especially since the new hollow point designs have improved as man stoppers causing many to return to the 9mm handgun.
(BTW 9mm is also much more forgiving on steel plate hanging targets ).
From a profit standpoint it seems the market is flooded with sub $700 AR carbines in .223 right now but Im not seeing many 9mm carbines in that price range (if any) especially with the S&W lifetime warranty.
The 9mm AR Carbine would also be much cheaper to build (shorter build time and less parts = Higher Co. profit ) since the operating system is simple blowback
(Right side 9mm bolt pictured below)
(Left side of 9mm bolt)
Simple blowback means the 9mm AR carbine does not require a gas tube, rotating bolt or locking lugs and as such makes the barrel much easier to machine at the breech, BTW it also does not require the forward assist assembly since the bolt does not lock into the barrel.
Colt simply pins a magazine adapter into their standard .223 lower mag well (pictured below) then adds a larger brass deflector,
If S&W wanted to "One up them" they could offer quick change adapters that would adapt various mags to their carbine,
In other words one adapter would accept M&P mags while another would adapt the carbine to accept Model 459/59 mags, another for CZ, another for Glock etc so the 9mm carbine could swap mags with the users choice of 9mm handgun should need arise.
A little 9mm Carbine plinking porn:
AR15 9mm - YouTube