The New Smith & Wesson Response 9mm Carbine: Review

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I was thinking that the FPC (Folding Pistol Carbine), introduced in 2023 and reviewed in Firearms News, was Smith & Wesson’s first pistol caliber carbine (PCC), but a bit of research gave me a surprise. S&W’s first PCC was the Model 1940 Light Rifle. That was a semi-auto rifle, chambered in 9mm and fed by 20-round magazines, made by S&W for Great Britain as they prepared for World War II. It was the opposite of a success, which is why you’ve probably never heard of it. But pistol caliber carbines are currently as popular as they’ve ever been in America, and S&W’s funky FPC was a success, so I was interested to test their newest PCC, the Response.

Unlike the FPC, the Response is an AR-15-based design, albeit with some unique features. Currently, there is only one Response model—it is chambered in 9mm and sports a 16.5-inch barrel. Like most 9mm PCCs, the Response uses a straight blowback action, which tend to be simple and reliable. The neat thing about the Response is that it has an interchangeable magazine well. From the factory it is set up to accept S&W M&P magazines, and two 23-round magazines are provided with the carbine, but S&W also provides a Glock magazine well with the carbine too, which accepts all Glock-pattern G17/G19 magazines. I will circle back to the “FlexMag” magazine well in a bit. The barrel has a black oxide finish and is threaded ½"x28 and a thread protector is provided. The barrel free floats inside the handguard, and here we come to one of the most curious features of the Response—the handguard, upper receiver, and lower receiver are all polymer. We’ve seen this before from Smith & Wesson, with their hugely successful M&P15-22 series. Polymer receivers/forends aren’t so unusual for a .22, but were unexpected for a 9mm from S&W.

The polymer handguard is 15-inches long and offers M-LOK compatible accessory slots. The finish of the polymer handguard and receivers is somewhat rough, and deliberately so, to give you some texture to grip. Midway down the handguard, you’ll see a row of M-LOK slots that are not cut out and instead sport the same aggressive texture as found in the M&P pistol grip. S&W also provides a number of aggressively textured rail/slot covers if you want a rougher gripping surface. You won’t need those rail covers to protect your hand from the heat—PCCs take forever to heat up unless you’re firing full-auto, and a polymer handguard transfers only a fraction of the heat you’ll get with an aluminum model.

There is a MIL STD 1913 “Picatinny” rail running full length down the top of the polymer handguard and the upper receiver. This will provide a good mounting surface for optics, but of course it will not be as strong as aluminum. You may think a polymer receiver isn’t tough enough for “duty” use and should only be reserved for competition guns…but a number of firearms with polymer receivers/rails are in use by military/police around the world, including the CZ Scorpion EVO. That said…I once managed to break the top rail off a CZ Scorpion EVO by dropping it on its Aimpoint optic. Just sayin.’

Unlike a standard AR-15, which uses a direct gas impingement system, the Response (like most 9mm PCCs of every design) is a straight blowback gun. The only thing cycling the action is the rearward force of the igniting cartridge, and the only thing counteracting/absorbing those forces are the weight of the bolt/buffer and the resistance of the buffer spring. Both need to be strong/heavy, so the bolt doesn’t move/chamber doesn’t open until some of the pressure and gases have dissipated. As a result, the bolts of blowback 9mm ARs like the Response are heavier than those on gas guns. Which is why, even with polymer construction, this carbine might not be as light as you expect—with no magazine in place the Response tips the scale at five pounds 14 ounces according to my scale. For comparison, the similar M&P15-22 MOE model weighs almost a pound and a half less (and is $230 cheaper, a point I’ll address later).

The first AR-pattern PCC was of course the 9mm submachine gun designed by Colt in the 1980s. There was a tab on those Colt stick magazine followers which pushed up on the longer bolt catch. Early AR PCCs, built to run on pistol magazines (most commonly the Glock), didn’t lock their bolts open on empty magazines, because manufacturers hadn’t quite figured how to do it. Luckily, that’s in the past, and the Response’s bolt locks back whether you’re running M&P or Glock magazines. The follower pushes up on a metal tab at the left front of the magazine well, which (through a linkage running along the top left of the magazine well) then pushes up on the standard AR-pattern bolt catch. This design uses a fixed ejector mounted just forward of the bolt catch.

When designing the first AR-pattern PCC, Colt engineers turned the bolt carrier group into a long heavy bolt, and since then everyone has pretty much followed that same design path. Smith & Wesson did too…but they also did something I haven’t seen before. Their stainless steel bolt is actually a two-piece design. In the center of the bolt you’ll see a pin, so the front and back half can separate. Weirdly, S&W doesn’t talk about this at all in any of their promotional materials—you’d think you want to talk up a unique feature. The bolt is thus modular (just like the mag well) and theoretically you could replace the back half with a heavier or lighter model (if and when available) to change your recoil impulse. The magazine release is a pivoting steel lever with a pad that should be easy to reach with the tip of your trigger finger no matter how small your hands are. The pad of the mag release is rectangular with a raised texture. The upper receiver is slick-sided, with no case deflector or forward assist. The charging handle, except for the latch itself, is polymer, which I found an interesting choice. In all of their promotional materials for the Response, weight reduction is the only reason S&W states for the use of polymer, but I know another has to be their FlexMag interchangeable magazine well system.

This is not the first time I’ve seen something like this for an AR, but all the previous designs I’ve seen have involved machined aluminum magazine wells, which are much more expensive to produce, and I suspect cost of producing the FlexMag in aluminum had S&W looking at polymer. You get S&W M&P and Glock magazine wells now with the Response, with plans for additional pattern mags. S&W announced a magazine well adapter to fit SIG P320 magazines at the 2024 SHOT Show. One minor complaint I had was the corners on the magazine well—they’re nearly sharp enough to draw blood, especially at the rear. There’s no reason for this.

For a gun that seems intended as much or more for competition than anything else I’m surprised the magazine well opening isn’t bigger or more flared. There’s a slight bevel, but that’s it. Big funnels are all the rage for the magazine wells of competition PCCs, and if S&W is looking at future improvements, they should offer a “competition” mag well for the Response—for Glock mags (as they are by far the most popular)—and sporting a huge beveled well. They should also be priced inexpensively, as competition shooters are legendarily cheap. And on that note, dedicated competition shooters put more rounds downrange than anybody else. Only a small percentage of gun owners ever shoot that much, but if you’re curious if the Response’s receivers will handle wear as well as aluminum after tens of thousands of rounds, we should be finding out in a year or so. However, as much testing S&W engineers did on the Response will pale in comparison to the abuse soon to be heaped upon it by the American public. However, as I said before, the Response is far from the first 9mm long gun with a polymer receiver, and other designs seem to be able to go tens of thousands of rounds without a problem. If anything, I wonder about the hammer pin widening the holes in the lower receiver, as 9mm blowback AR blowback bolts are legendarily hard on hammers.

Inside the lower receiver you’ll find a trigger group they made specifically for the Response, although it does accept all AR-pattern trigger groups. The trigger is straight, with a flat face, and I like the looks and feel of it. The hammer and trigger sport MIM construction and provide a standard unimpressive GI-style trigger pull—single stage with a bit of a rolling break, with a hint of grit, for a total 6.0-pound pull in my piece. The selector is steel, and had a bit of a gritty throw in my sample. On the left side of the lower receiver, above the trigger and hammer pins, you’ll see a rectangular cutout showing a stainless-steel plate, on which is etched the gun’s serial number. I was curious if this was just a plate set into the polymer, or if it was just a section of steel cage embedded into the lower receiver all the way around. I popped out the hammer pins and looked, and it appears the lower receiver is 100% polymer, that plate is just that. The polymer receivers are beefed up in a lot of places when compared to an aluminum receiver, especially at the rear. The Response uses a standard aluminum AR-15 buffer tube and spring. The buffer is a standard (heavyweight) pistol buffer. On the buffer tube you’ll find a Magpul SL stock. Between looks, performance, and price I feel that this is the very best Magpul adjustable carbine stock. The Response accepts standard AR-15-pattern grips, and comes with an M&P grip identical to those found on the S&W M&P semi-auto pistols. Supplied with it are the standard four (S, M, ML, L) interchangeable backstraps. This provides you with a more vertical grip angle than the traditional A2-style pistol grip. The texturing on the pistol grip and backstraps is nearly as aggressive as stippling.

Swapping out the FlexMag magazine well takes a few minutes. Lift off the upper receiver after popping out the two standard receiver pins, front and rear. There is a set Allen screw holding the bolt catch assembly in place—unscrew that (it’s captured) and the bolt catch assembly comes out the top of the lower receiver. Once that is removed you can slide the magazine well off sideways. Note that not only is the magazine well different for each type of magazine, but so is the steel piece that the magazine follower pushes up on to lock the bolt back. The pieces made for the M&P magazine are marked with an M on the right side of the magazine well, just forward of the trigger guard, and on the top of the steel piece pushed up by the follower. The corresponding Glock parts are marked with a G. The instructions in the owner’s manual are accompanied by a number of photos and pretty easy to follow. PCCs are fun to shoot, whether you’re talking plinking at the range or competition. They’re great to train new shooters on as well. I personally think pistol-caliber carbines are the best choice for home defense as a general rule, between the ease they can be aimed, lack of recoil and noise (when compared to a rifle or shotgun), and capacity.

At the range the Response was completely reliable. I put several hundred rounds through it using the M&P mag well, then switched it out for the Glock and used that for the remainder of my testing. Both worked perfectly. Recoil was as expected—just a bit more than a gas-operated AR-15 but still mild. Accuracy was comparable to most other PCCs I’ve tested. PCCs are inherently not as accurate as rifles, but they’re still far quicker and easier to shoot at distance than pistols no matter your skill level. With a red dot, even unskilled shooters can regularly hit a man-sized target at 100 yards with a PCC, and at urban defensive distances for most people there’s no comparison to a pistol for speed and accuracy. I knocked down at bit of steel at my club, and did some reliability testing with a few different JHPs, but precision work is a bit tougher when the snow is on the ground and the temperatures are in the single digits and you’re a delicate little princess who starts to shiver if the temperature dips below 60. I did my accuracy work at an indoor range. There’s absolutely nothing wrong with the S&W Response, but at the end of my test and evaluation, I guess I remain a little confused about S&W’s choice of polymer for their construction of the Response. Traditionally, polymer is chosen because it is cheaper than the alternative, but that cost savings doesn’t seem to be reflected in the price of the Response. You can find all-aluminum 9mm ARs on the market priced less than the Response. No, they’re not from a company of S&W’s stature, and they don’t have interchangeable magazine wells (with *cough* pointy corners), but still, S&W’s increased production capacity (you’d think) would equate to lower costs. The S&W Response was fun to shoot and reliable, but the polymer construction makes it look and feel like it should cost less than the suggested retail price.

Smith & Wesson Response Specs

• Caliber: 9mm
• Weight: 5 lbs., 14 oz. 
• Overall Length: 32.2 in. (collapsed), 35.3 in. (extended)
• Receiver: Polymer
• Finish: Matte
• Barrel: 16 in., 1:10-in. twist, black oxide finsih, 1/2x28mm threaded
• Muzzle: None, thread protector
• Stock: Magpul SL
• Grip: S&W M&P, interchangeable backstraps
• Forend: Polymer, M-LOK 15 in. 
• Trigger: Single-stage, 6 lbs. (tested)
• Sights: None
• Accessories: Two 23-round magazines, four backstraps, cable lock, Glock-pattern FlexMag, polymer rail covers
• MSRP: $799.00
• Contact: Smith & Wesson

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