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New Mossberg 940 JM Pro Competition Shotgun

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When you hear the word Mossberg, there’s a good chance that you think of shotguns. And when you hear the name Miculek, you probably think “shooting legend.” Put them together, and you have the brand new Mossberg 940 JM Pro 12-gauge semi-auto competition shotgun that Mossberg designed in conjunction with the incomparable Jerry (and Lena) Miculek.

Over 15 years ago, Mossberg launched the 930 series of gas-operated shotguns, later releasing the 930 JM Pro competition gun, specced out by Miculek. So, it’s been a little while, and Mossberg is stepping back up to the plate. The new 940 platform is updated and upgraded in a number of ways, with the tricked-out JM Pro version leading the way.

The New and Improved Mossberg 940 JM Pro Shotgun

Most importantly, the 940 has a new, redesigned gas system that Mossberg says will happily go 1,500 rounds between cleanings — addressing a frequent sore point with the old 930, especially for 3-gun competitors who put a lot of rounds downrange. The piston has a self-cleaning design, and the spacer tube is vented and stepped. The short stroke piston also never leaves the cylinder during operation, so you won’t break a gas ring. The piston and piston ring are nickel-boron coated.

The 940’s receiver is lightweight anodized aluminum, drilled and tapped on top for optics. The charging handle and bolt release button are enlarged and aggressively contoured for empty-chamber starts and oh-shit moments when you run the gun dry. The hammer, sear, and magazine tube are also nickel-boron coated.

Loading the shotgun is critically important for 3-gunners who compete in the tactical optics division. The 940 JM Pro’s loading port comes hogged-out from the factory and is extensively enlarged, beveled, and smoothed. The lifter is lengthened and solid, eliminating the evil prongs on so many other shotguns that try to rip the nail off of your thumb. A bright orange anodized aluminum follower peeks out of the magazine tube, which has also been contoured at the loading port. The foreend is streamlined and won’t interfere with loading. The combination of all these touches result in a shotgun that’s tuned and optimized for quad-loading, a technique by which competitors hold four shells in their hand, loading two at a time quicker than you can say “Lena Miculek.”

The barrel is 24-inches long, with a HIVIZ fiber optic front sight. The JM Pro comes with a set of Briley extended chokes so that you can easily select and install exactly the choke you want for each stage, based on the targets and distances in the course of fire. Cylinder, improved cylinder, and modified chokes will be supplied with the gun.

The included magazine tube stretches to the muzzle (but not the tip of the extended choke), holding nine 2.75-inch shells. 3-gunners will no doubt immediately look to swap it out for even longer magazine tubes to joust with. The gun doesn’t come with a barrel clamp, making it straightforward to maintain a consistent zero with slugs.

The fit of a shotgun to the shooter is extremely important, and the 940 JM Pro’s furniture is also all-new. You can adjust the buttstock for length of pull, cast, and drop. To adjust length of pull, unscrew the recoil-absorbing buttpad, then add or remove stock spacers to taste — the total length of pull ranges from 13 to 14.25 inches. To adjust the drop at comb or cast, remove the buttstock and select the appropriate stock shims. Cast adjusts approximately 0.125 inches left and right, while drop and rise has about 0.5 inches of total travel. This allows you to dial in the stock for consistent and repeatable presentation. The slim foreend and grip are aggressively textured without being obnoxious.

The top-mounted safety selector, charging handle, bolt release, trigger, and magazine tube nut are all brightly finished for a dash of color on the version of the 940 JM Pro with a tungsten grey receiver and black furniture. There’s also a variant with black Multicam furniture and a black receiver.

At the Range

To shake out the new shotgun, we spent several days at our gracious hosts at Gunsite in Arizona with none other than Jerry and Lena Miculek themselves, in addition to the capable staff at Gunsite.

Jerry loaded the gun up with his light 3-gun match ammo, and even with his machine-gun finger, he couldn’t outrun the gun when doing mag dumps. We tried our best as well; the 940 is fast-cycling gun and a sweet shooter. It shoulders comfortably and points intuitively. We didn’t get an opportunity to shim the gun to fit, though, which would have made it even better. We shot bill drills to dial in our stance, grip, and recoil management. We shot multiple targets to test target transitions. We shot more, just to shoot more. The Mossberg was an absolute hoot.

Lena ably demonstrated how even a petite individual with small hands can load and shoot a 12-gauge like a champ. Oh wait, she is a champ — a world champion in several different disciplines. Not surprisingly, her technique is honed to a razor’s edge, and we were able to apply it on the 940 JM Pro under her tutelage. Trying to quad load shotguns can make you feel like a clown, spraying shells all over the ground like fertilizer. But with good and consistent technique, it’s achievable. And the JM Pro sets you up for success.

Mossberg really got it dialed in; it's impressive for a factory gun. If you've attempted to modify and tune your own guns (as we have with a pricey Benelli), you know how painstaking it can be, as you gradually remove material from the gun, always worrying that you’ll take it too far and ruin your gun. Alternately, you can send your gun to one of the talented shotgun gunsmiths out there, who do great work but at a premium. The 940 JM Pro is truly ready to quad load, out of the box. You’ll need some good shell caddies, though; the King Competition caddies we were using worked great.

The Mossberg’s trigger was reasonably light and broke cleanly, helping with shooting slugs. We shot standard and low-recoil slugs at 50 yards to check zero. The low-recoil slugs were pretty well zeroed, while we had to hold off a fair amount with the standard ones. Then, we ran the Gunsite scrambler course with the standard slugs, as we didn’t have enough of the low-recoil slugs. This was a blast, though a bit tough on the shoulder. Once we got the hold figured out, we drilled steel after steel with the JM Pro out to about 75 to 80 yards.

Mossberg touts the new 940 JM Pro as competition-ready, right out of the box. It certainly is, based on our couple days with a pre-production gun. Reliability, however, is critical for a competition gun. If you Google the previous 930 JM Pro model, you’ll find many passionate debates on user forums about its reliability. Mossberg has specifically addressed this in its redesign for the 940. This improvement landed the 940 a high rank among tactical shotguns available in 2020.

We put a few hundred rounds through the 940 JM Pro. Early on the first day, which was cold and rainy, we experienced one stovepipe and one shell which sat on the lifter. For the former, it could have been the dry gun, the light load in cold and wet weather, or perhaps we were holding the gun too loose at the time; it didn’t happen again. The latter was the last round in the magazine, so it could have been due to a light magazine spring slowing it down and preventing it from chambering. We had no other functioning issues throughout the rest of our time with the gun. One small issue was the magazine tube nut, which kept loosening under recoil — Mossberg said this will be fixed in the production guns.

With an MSRP of $1,015, street prices should be even lower, making the Mossberg 940 JM Pro competition shotgun an attractive buy for use in competition. All you might want to add is a longer magazine tube. The new gas system should continue to be reliable; we look forward to putting a production gun through its paces throughout a match season. An initial batch is expected to hit distributors this month.


Mossberg 940 JM Pro Shotgun

Caliber: 12-gauge (3-inch chamber)
Barrel: 24 inches
Capacity: 9+1 (2.75-inch shells)
Length: 44.75 inches
Weight unloaded: 7.75 pounds
Colorways: Tungsten grey receiver with black furniture, black receiver with black Multicam furniture
MSRP: $1,015

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