Mossberg 940 Pro

Bring Boom To The Room
; .

Mossberg’s 940 is a refined tool designed to be used hard with
modern gun-handling techniques as well as accessories like a dot and light.

Competition betters the breed. This has been common knowledge since the halcyon race days of the ’60s when the automaker’s slogan “win on Sunday, sell on Monday” ruled the roost. In fact, the earliest races were contests less of speed than reliability, for manufacturers to prove the durability of their wares. It’s not all that different with defensive guns — many of the innovations we take for granted came from competition. Think red dot sights, the 2011, etc. Among the latest platforms to benefit has been Mossberg’s formidable 12-gauge semiauto, the 930, which has been substantially upgraded to create the 940 Pro.


Mossberg’s 940 Pro builds directly on lessons learned from
the 930 being wrung out in the crucible of 3-Gun competition.
It stays cleaner — reducing cleaning intervals — and handles and loads faster.

Payload Plus

And yes, I know carbines are more popular these days even for home defense. But the shotgun does what it’s always done, which is deliver a heavy, fight-stopping payload at close range. It’s hard to imagine something doing it more efficiently than a semiauto 12 gauge. I’ve gotten split times between shots down to 0.18 seconds with a 930, which is pretty quick for sending out the equivalent of a mag full of 9mm.

Introduced 15 years ago, the 930 SPX Tactical combined the gas system of the 930 with state-of-the-art features for the time: 7+1 capacity, an 18 ½” cylinder-bore barrel, a pic rail with removable ghost ring rear and matching AR-style front sight tower with ears to protect the fiber optic front. After spending some time with a 930 SPX Tactical at Gunsite, I liked it enough to buy one, the gun writer’s second highest compliment. I used it as a defensive gun, which is the highest. A serious piece of equipment for serious use, it is, at its heart, a buckshot gun.

It also proved tremendously popular for 3-gun competition, and as light loads and new reloading techniques became more prevalent, areas for potential improvement appeared. The engineers at Mossberg, who are no fools, took a good look at 3-gun champion Jerry Miculek’s competition gun and began to morph the 930 into something a lot like it. Voila: the 940 Pro.

The barrel looks a little thicker at the muzzle, a dead giveaway for the interchangeable choke system, an acknowledgement this gun isn’t limited to buckshot and slugs. It comes with a flush cylinder bore tube installed, and additional Accu-Chokes are available from Mossberg (the competition-oriented JM PRO shotgun comes with extended Briley tubes). The 930’s red fiber optic front sight remains, but that’s it — it mounts directly to the barrel without the tower, which is rendered unnecessary since there is no pic rail in the rear and no ghost ring clamped atop it.

The receiver is drilled and tapped, so feel free to add a rail. I didn’t put a caliper on it, but the hole spacing looks the same as the 930. In its place the receiver has been machined to accept a direct-mounted optic. Personally, I like a ghost ring but the added height of the original system makes it harder to get a good cheek weld on the gun, increasing recoil and making it harder to use an optic.


The magazine tube clamp serves as a sling mount or for other
M-Lok compatible accessories like a flashlight. It also provides
added support to the mag tube extension should the gun be dropped.

Dot The Eye

These days we put optics on everything — I just mounted one on my Spyderco. What was once a competition-only device has become small and rugged enough for general use and the lower pocket-style mount makes it much more practical to use one on the 940. It accepts RMSc footprint optics and comes with a cover plate installed. Sadly, my Holosun 507 doesn’t have the right footprint but I had an older Trijicon dot I used instead.

Internally, the gas system has been modified for added reliability including a corrosion-resistant nickel-boron coating on some components and ventilated spacer tube. A feature pioneered by OR3Gun Inc., the vented tube lets spent gas and other debris exit faster to reduce buildup in the gas system, and likely accounts for the lengthier cleaning intervals offered by the 940. On the outside of the magtube, a polymer barrel/mag clamp adds a reversible sling swivel and one M-Lok slot per side for mounting a flashlight or other accessories. It also provides extra support for the screw-on mag extension, should the gun be dropped.

The safety remains in its familiar location on top of the receiver, easy to reach with either hand, and the cocked-hammer indicator inside the front of the trigger guard is also unchanged. Meanwhile the bolt handle is larger, knurled and round, and the bolt release is substantially larger than the 930’s round version. Both features help with fast manipulations.

A friend of mine who’s a nationally ranked USPSA shooter tells me he’s not interested in 3-gun because it’s basically a shotgun reloading competition. He’s not wrong; doing it fast is hard but makes up a lot of time. Bigger controls aren’t the only thing. Efficient reloading includes twin-loading — hold two rounds end-to-end in your hand and sweep them down the bottom of the gun, driving both into the mag tube through the loading port. Once you master this comes quad load with two stacks side-by-side.

This technique explains the trim lines of the 940’s forend, which has no frustrating step where it meets the receiver since it would stop your hand from sweeping forward during twin loads. It also explains the nicely opened up port which is beveled all the way around and the flat-ended elevator (aka, “lifter”), which eliminates the commonly found notch that so enthusiastically seizes your thumb when pushing shells in. A hi-viz aluminum follower lets even the most inattentive range officer know your gun is empty at the end of a stage and is colored orange to contrast with the usual red and green shotshells.


The 940 gas system has been modified for added reliability
including corrosion-resistant nickel-boron plating and a
ventilated spacer tube.

The 940 Pro includes the cocked hammer indicator to provide
tactile confirmation of whether or not the gun is cocked. If it sticks
out, the gun is ready to fire … if not, the hammer is not cocked
and the gun isn’t ready to rock.

The loading port is nicely opened up and beveled all the way around.
The shell follower is high-visibility orange and beveled for reliability.

The flat-ended elevator (aka, “lifter”) eliminates the notch found
on the 930 that so enthusiastically seizes your thumb when pushing shells in.

Max Cap

Capacity is listed online as 7+1 and in the manual as 6+1; mine held six in the tube but you can “ghost load” the 940 by slipping an extra cartridge beneath the bolt and onto the lifter, making total capacity eight, but we’ll come back to this. Candidly, I think six instead of seven is a good decision. Springs take up room. Add another 2 ¾” shotshell and the spring has to be made of thinner, weaker wire or have fewer coils even though it’s now pushing a heavier load. My 930 held seven but ate springs so frequently I sacrificed the extra shell for a stronger spring and added peace of mind.

The black polymer buttstock comes with an impressive complement of shims for both the rear and front to adjust for length-of-pull, rise (whether it tilts upward or downward) and cast (whether it angles to the left, right, or is straight in line with the barrel). Mine also had an extra thin recoil pad. However you’re shaped, the 940 ought to fit you.

When people say “it must be nice to get paid to shoot,” I often think of an afternoon several years ago patterning buck, slugs and 3″ magnums from the bench. My shoulder kept the memory fresh. The 940, however, is surprisingly comfortable to shoot. I put around 200 rounds through it, about 40 of which was birdshot. The rest was buck and slugs, which never hurt me.

The only malfunction I had was when a ghost-loaded round didn’t feed properly. I was never able to duplicate it, though I tried a dozen or so more times. Loaded as intended, it never bobbled though I never cleaned or oiled it. Word to the wise: Save ghost loading for the range, not for defense.
Shotgun ammo ranges from super light bird loads to heavy 3″ magnums, and any mechanism capable of managing such a broad array of recoil impulses is a serious engineering accomplishment. Remember John Browning invented gas operation but stuck with recoil operation when he created the first semiauto shotgun — and even it had an array of friction rings that need adjustment based on the kind of ammo you were shooting. From this backdrop, the gas-operated 940’s ability to function with everything is particularly impressive.


At 50 yards, the 940 put all of the slugs into one ragged hole.
Considering you can quickly put 700+ grains of lead into a
palm-sized group at most fighting distances, the .223 begins
to look a little anemic.

The 940 Pro comes with an unusually comprehensive set of spacers
and shims allowing you to adjust length of pull, cast and rise
to fit almost any body shape and size.

Buck It Up

You often hear buckshot spreads about 1″ per yard, but the 940 Pro did a good deal better, usually putting all its pellets in 4″ to 5″ at 7 yards, with several groups in the 3″ range. Ten-yard patterns ranged from 5 ½” to 8″ and the few groups I shot at 25 went from 15″ to 21″, basically covering the chest area of a target. This is the distance at which the shotgun’s oft-misunderstood increased hit probability really comes into its own, at the cost of the payload it delivers, and should be considered its maximum range.

Federal provided both 00 and #1 buckshot for the test. While I’m fairly devoted to 00, the #1 Maximum Buckshot is well-named. I think the term is “dense pattern” but if you were painting a car you’d say the 16 .30 caliber pellets give good coverage.

The 940 can be purchased with a Holosun installed but my small Trijicon dot showed the gun particularly adept at sending slugs where I wanted them. Shotguns are the only small arms whose projectile changes size in flight. This is what makes it a thinking person’s weapon and why it’s important to pattern your gun with your chosen ammo so you know exactly where those pellets will go at each distance. While I used a simple red dot, the rings of some reticles may line up with the pattern size at some distances, but you’ll have to learn that on your own by trial and error. Me personally, I’ll leave the more complicated reticles to others and stick with a dot zeroed for slugs. At 50 yards, there was’t really a group to speak of. They just tore a huge hole, like Sonny Liston’s fist went through the paper.

And now we’re back to knockout blows — exactly what the shotgun does best and the 940 does exceptionally well. While a top-level competitor would probably benefit from the JM version of the 940, the Pro is well-thought out enough to run in matches and still sit reassuringly by the nightstand for home defense. Win on Sunday, live on Monday.

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