Mossberg 940 JM Pro 12 Gauge 24in 9+1 MultiCam
About this product
The Mossberg 940 JM Pro is a 12-gauge semi-automatic competition shotgun built for 3-Gun and tactical shotgun matches, featuring a gas-operated system and adjustable MultiCam synthetic stock. It's built on the established 930 platform but refines the gas system and adds more competition-specific features straight from the factory. This particular configuration includes an optic-ready Shield RMSc-cut receiver and a 24-inch vent-rib barrel.
What is the Mossberg 940 JM Pro 12 Gauge 24in 9+1 MultiCam used for?
This shotgun is purpose-built for dynamic shooting competitions like 3-Gun, where speed, reliability, and shot-to-shot consistency under time pressure are critical. The gas system is tuned to cycle a wide range of loads, from light 1-ounce target loads to full-power buckshot, which is essential when a stage might require both. The adjustable stock and optic-ready platform allow a shooter to tailor the gun to their physique and preferred aiming system without aftermarket machine work.
How does the Mossberg 940 JM Pro compare to the Stevens 555 Sporting O/U?
The 940 JM Pro is a faster, higher-capacity platform designed for speed shooting, while the Stevens 555 Sporting is a break-action over/under built for deliberate clay target games like trap and skeet. The JM Pro's 9+1 capacity gives a significant advantage in stages requiring multiple targets without reloading, whereas the Stevens 555 offers the inherent precision and pointability of a fixed-barrel design for breaking clays at longer ranges. For running and gunning, the semi-auto is objectively better; for traditional shotgun sports, the over/under is the standard.
What does it weigh and what are the dimensions?
The shotgun weighs 7.75 pounds unloaded, with an overall length of approximately 46.5 inches given the 24-inch barrel and collapsed stock. The length of pull is adjustable from 13 inches to 14.25 inches using the included spacers, and the drop can be changed with the provided shims. This adjustability allows most adult shooters to achieve a proper cheek weld and eye alignment, whether using iron sights or a mounted red dot.
Who is this NOT for?
This is not a suitable first shotgun for a new shooter focused on home defense or casual clay shooting. The competition-focused controls, like the oversized bolt release and textured charging handle, are optimized for speed drills, not simplicity. The gas system also requires more attentive cleaning after several hundred rounds of cheap, dirty ammunition compared to a simple pump-action like a Mossberg 500. If you're not planning to compete or run high-round-count training drills, you're paying for features you won't use.
What's in the box?
You receive the shotgun with a Briley-style extended cylinder choke (threaded for Mobil chokes) installed, three stock spacers for length of pull adjustment, two stock shims for comb height adjustment, and a basic set of Allen wrenches for making those adjustments. Notably, it does not include a red dot sight—the receiver is cut and ready for one, but you supply the optic. The manual includes clear diagrams for disassembly, which you'll want to review before your first range session.
Is the Mossberg 940 JM Pro worth it at $1047.99?
At just over a thousand dollars, it's a competitive entry into the dedicated competition shotgun market, undercutting custom-tuned Benelli M2s by several hundred dollars. You are paying for a factory-tuned gas system, an adjustable stock, an optic cut, and a MultiCam finish that would cost significantly more to add aftermarket. If you are serious about moving up from a basic pump or hunting semi-auto into competition, this package eliminates about $300-$500 in common first upgrades. For a pure hunting gun or range toy, look at the standard Mossberg 940 field models for about $200 less.
Specs at a glance
Video review
Pros & cons
What works
- Optic-ready Shield RMSc-cut receiver — saves $150+ on aftermarket milling
- Adjustable length of pull (13" to 14.25") and drop — fits 90% of adult shooters without modification
- Nickel boron-coated internal components — reduces friction and extends cleaning intervals to 500+ rounds with quality ammo
- Includes extended cylinder choke — improves shot pattern consistency for close-range steel targets
Trade-offs
- Gas system requires detailed strip-down for proper cleaning — adds 15-20 minutes to maintenance versus a pump-action
- MultiCam finish is cosmetic only — provides no corrosion resistance over the base aluminum and steel
- No shell carrier or side saddle included — essential for 3-Gun, adds $40-60 and installation time
Expert review
Key attributes
| upc | 015813851664 |
| manufacturer | Mossberg |
| manufacturer part number | 85166 |
| action | Semi-Auto |
| atf type | Shotgun |
| barrel finish | Matte Blued |
| barrel length | 24" VR |
| caliber/gauge | 12 Gauge |
| capacity | 9 + 1 |
| chokes included | Extended |
| color | Blue |
| length | 46.375 |
| package height | 3.6 |
| package width | 9.1 |
| product type | Shotgun |
| safety | Tang |
| shipping weight | 10.55 |
| sights | Front Fiber Optic Sight |
| sights type | Fixed Sights |
| state restriction (il) | NO SALE TO ILLINOIS PICA |
Frequently asked questions
- Is it compatible with Benelli Mobil chokes?
- Yes, the included Briley extended choke and the barrel threads are cut for the standard Benelli Mobil choke system (Mobil, not Mobil*Long*). This gives you access to hundreds of aftermarket choke tubes from brands like Carlson's, Patternmaster, and Trulock for tuning your pattern.
- Does it fit in a standard 48-inch rifle case?
- Yes, with the stock adjusted to its shortest 13-inch length of pull, the overall length is approximately 46.5 inches. It will fit diagonally in most standard 48-inch soft or hard rifle cases with room for a choke tube wrench and cleaning rod.
- How long does shipping take to an FFL?
- Ironclad Armory processes in-stock items within 1 business day. Shipping transit time depends on your location and carrier, but most continental US shipments arrive at your selected FFL dealer within 3-7 business days from the date of order. You will receive tracking once it ships.
- Can I return it if I don't like it?
- All firearm sales are final once transferred through an FFL, due to federal regulations. We strongly recommend you handle a 940 JM Pro at a local dealer or match before purchasing. We will, however, fully support any warranty repair through Mossberg if there is a mechanical defect.
- Does this work with a Magpul SGA stock?
- No, the 940 JM Pro uses Mossberg's proprietary stock mounting system with its integrated recoil system. The Magpul SGA stock is designed for Mossberg 500/590/88 series pump-action shotguns and is not compatible with the 940's semi-automatic receiver.