Mossberg's 12 Gauge Semi-Auto 940 Pro Tactical: Field Tested

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I’m not sure when we stopped calling them “riot guns,” but considering how many billions of dollars of damage and dozens of deaths have been caused by riots in this country in recent years, I vote we bring back that term. Especially, since it seems so politically incorrect. Generally, a “riot gun” is a shotgun that has been specifically designed or modified for defensive use, as opposed to one meant for hunting. Riot guns have shorter barrels, and often a longer/extended magazine tube. This brings us to the subject of this article, the new Mossberg 940 Pro Tactical.

“Pro Tactical” sounds much more PC than riot gun, but a rose by any other name… Mossberg’s semi-auto 940 Pro shotgun is set-up for defensive use, and a better choice for that task you will be hard pressed to find. First, let’s look at the numbers; the Mossberg 940 Pro Tactical is a 12 gauge shotgun with an 18.5-inch barrel. It takes Mossberg’s Accu-Chokes, and a cylinder bore choke is installed at the factory. Below the barrel is an extended magazine tube, and capacity is 7+1 with 2¾-inch shells. The barrel and magazine tube are steel, and the receiver is aluminum, and all metal sports a matte black finish. Total empty weight of the shotgun is 7 pounds 8 ounces. Mossberg states the shotgun is 37.5-inches long. As it comes from the factory, with one buttstock spacer installed, it’s 38.75-inches long. The forend and buttstock are black polymer, and the buttpad is quite soft. My biggest, and perhaps my only complaint about this gun, is that the forend feels cheap.

The 940 Pro Tactical sports a traditional Mossberg receiver safety that is as easily used by left-handers as right. The serrated button is aluminum. Both the steel bolt handle and the polymer bolt release are oversize for positive manipulation. The magazine follower is aluminum and anodized a high-visibility metallic orange color. The front sight is a red fiber optic bead from LPA, but at the rear you’ll see the receiver is cut for miniature optics utilizing the Shield RMSc footprint, more on that in a bit. The barrel/magazine tube clamp is a beefy piece of polymer that has a 1.25-inch M-LOK slot on either side for mounting accessories such as slings or lights. There is also a sling swivel screwed into the left side that can be switched over to the right, or removed entirely.

The 940 is a replacement for Mossberg’s 930, which wasn’t quite the success they’d hoped for, as apparently their testing wasn’t as abusive as real-world hunters and 3-gunners. But the lessons they learned have gone to make this shotgun a significantly better performer. Both the 930 and 940 were gas piston-operated shotguns. The 940 features enlarged gas ports and a single piston ring. In fact, the redesigned self-cleaning gas piston directs gases away from the magazine tube, keeping it cleaner. Fouling of the gas system was a big problem with the 930. Mossberg advertises that this shotgun can go up to 1,500 rounds between cleaning. There is a nickel-boron coating on the end of the magazine tube, gas piston, gas ring, hammer and sear.

This tactical shotgun benefits greatly from competition-directed improvements. These were done at the request of Mossberg-sponsored competition shooters Jerry and Lena Miculek, for their 940 JM Pro competition model. The shell lifter (elevator) has been extended to drastically reduce the chances of your finger getting pinched while loading, which has long been a pet peeve of mine. There is now an eighth of an inch or less between the end of the lifter and the magazine follower/shell. The loading port has been enlarged for easier loading, and there are no sharp edges. While users of this shotgun are unlikely to be doing the 3-gunner/John Wick dual or quad loading for which this enlarged port was designed, the larger port and lack of sharp edges benefit anyone who has to shove a shell into the gun.

The stock is adjustable for cast, drop, and length of pull using the supplied spacers, and Mossberg supplies a second, thinner rubber buttpad. This feature is brought over from the competition model. While being able to shorten up the LOP is useful (between spacers and buttpad it’s adjustable from 13–14.25-inches), I’m not convinced that adjustable cast and drop are something you want, or need on a defensive shotgun. For defensive purposes, pump-action shotguns have traditionally been considered superior to semi-autos due to reliability concerns. Semi-auto shotguns weren’t as inherently reliable as pumps in general, and then they often would cycle light birdshot, or heavy buckshot, but not both. However, all of that seems to be in the past. All of the semi-auto defensive shotguns I’ve tested over the past few years, Remington V3 Tactical, LTT Beretta 1301 Tactical, Benelli M4 Tactical, and now the Mossberg 940 Pro Tactical (can we all agree that “tactical” is overused?) proved themselves to be 100% reliable with all types of ammunition.

Before I dive into the “optics ready” feature of this shotgun, I need to cover a little recent history. Mossberg originally planned to release the 940 Pro Tactical at the end of 2021, and the release was delayed by six months. I will take at least partial blame for that, but trust me the end result is a significantly improved product. Mossberg brought out a dozen or so gunwriters to Gunsite in June 2021 where they showed off their two planned 940 Pro Tactical models, as well as the MC2sc pistol. We shot pistols and shotguns over two days at the oldest privately-owned firearms training facility in the world, and if you have a chance to go to Gunsite, GO. Anyway, one of the proposed 940 Tactical models had a simple fiber optic front sight which worked just fine. The other had a tall, robust ghost ring sight set, with a rail forward of the rear sight for mounting an optic. The only problem? Those sights were far too high, and required the shooter to pull their face off the stock to see through them. But…the Mossberg people also brought two prototype shotguns along, customized by their engineers. They were the fiber optic sight models, only with the receiver directly milled for a red dot. These custom models were by far the most popular, and we media types were unanimous in recommending to Mossberg that they offer it as a model. And they took our advice, while at the same time making a few tweaks to the design of the bolt release. The end result is what you see here.

The original bolt release was flat, round, and aluminum, a basic black version of the release seen on the 940 JM Pro competition gun. However, the bolt release on the production gun is different, both in appearance and function. It is polymer and extends forward underneath the bolt handle. Why the weird shape? Short answer, it’s just to differentiate this from the other 940 models. But, that brings us to the “quick-empty magazine release.” Mossberg on their product page is happy to point out that this shotgun has what they call the “quick-empty magazine release.” But they don’t say where it is, or what it does. Turns out by “quick-empty magazine release” they are referencing the shell stop inside the receiver, and if you push up on the elevator, and push in on the shell stop, with a finger you can easily strip a shell out of the magazine.

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However, while waiting for Mossberg to get back to me on this, I did a little experimenting with the 940, and discovered that if you depress the lifter a bit as you’re pulling the bolt back, and hold the bolt back while you pull on the bolt stop, all the rounds in the magazine will eject (FYI it’s impossible to accidentally do this). I thought that might be the reason for the redesign of the bolt release, to make it easier to pull for this “speed unload” feature. Nope. Turns out even the Mossberg engineers weren’t even aware this little trick was possible. The receiver cut is for the Shield RMSc (compact) sight, which is smaller than the standard RMR/Doctor/Delta Point-size optic. However, utilizing that smaller, narrower sight means that it won’t overhang the edges of the receiver, while still being more than large enough to work very well. After all, those optics are meant to mount atop pistols at arm’s length, and on this Mossberg it’s sitting just six or so inches in front of your face, so that window seems much larger.

For testing I used a Holosun 507K, which gives you the option of a simple dot or a circle/dot reticle. No matter which optic you’re using, you’ll be able to see that fiber optic front sight at the end of the barrel through the window. So, you should figure out how to sight your shotgun using that front sight through the optic’s window, as batteries die and electronics fail. The top of the optic body is higher than the receiver, so placing that red bead at the bottom of the window likely will put your shot pattern high. The 507K body has a bit of a rear sight notch machined into it. With the Mossberg’s red fiber optic bead nestled inside it, at 25 yards I had to aim at the silhouette’s belt buckle to put the pattern in the target’s chest. Your experience may differ, especially if you’re running a different optic, which is why you always need to pattern your shotgun with various loads, and learn how to use your sights—conventionally and otherwise.

Let me repeat that again, every shotgun performs differently, so you need to pattern your gun with whatever loads you want to use. As part of my testing I decided to pattern the 940 with the most popular defensive load in the country, Federal’s reduced recoil 9-pellet 00-buck load, at both 7 and 25 yards. At 7 yards this shotgun produced the tightest patterns I’ve ever seen with this ammunition. Seriously, I had to fire several more shots than expected, simply because I thought the pattern had somehow missed the target and what I was looking at was simply the hole from the FliteControl wad. Over and over again this ammo would do 1–1.5-inch groups at 7 yards. At this distance, the wad was barely separating from the shot column. It all made a single hole.

At 25 yards this load, out of this shotgun, put a nice 7.25-inch pattern on the target. That’s great, if you want a tight group. Maybe you’re only planning on using this for home defense, where your longest shot is 10 yards, and you want a larger pattern. The great thing about the shotgun is its versatility. You can change up your shot size, ammunition type, even your choke, to get exactly the results you want. I found the Mossberg nicely pleasant to shoot. Part of that is due to the weight, but part also is due to its gas-piston operating system. With birdshot it was soft and you could shoot it all day. Reduced-recoil buckshot barely has any more recoil than birdshot. Trigger pull was very nice, with a little bit of takeup before a crisp, five-pound break. The Mossberg 940 Pro Tactical isn’t perhaps as polished at the two leaders in the semi-auto tactical shotgun field, the Benelli M4 and the Beretta 1301, but it is significantly less expensive than either of them, while offering unique features and nearly equal performance. If you’re in the market for a semi-auto riot gun, I think this one is a serious contender.

Mossberg 940 Pro Tactical Specs

• Type: Gas-operated, semi-auto
• Caliber: 12 gauge, 3-in. chamber
• Barrel Length: 18.5 in. 
• Stock: Black Synthetic
• Receiver: Aluminum
• Muzzle Device: Accu-choke (cylinder bore installed) 
• Overall Length: 37.5 in. 
• Weight: 7 lbs., 8 oz. 
• Safety: Manual
• Sights: Fiber optic bead, Receiver cut for RMSc-pattern optics
• Trigger: 5 lbs. (tested) 
• Accessories: Choke wrench, adjustable stock spacers
• MSRP: $1,120
• Manufacturer: O.F. Mossberg & Sons

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The articles was originally published in Be Ready! Magazine. You can find an original copy at OSGnewsstand.com. If you have any thoughts or comments on this article, we’d love to hear them. Email us at FirearmsNews@Outdoorsg.com.