Mossberg 940 JM Pro 12GA 24in Optic-Ready 9+1
Pros & cons
What works
- Gas system cycles 1,200+ rounds between cleanings — 3x longer than inertia-driven competitors
- Optic-ready receiver accepts Shield RMSc pattern dots without gunsmithing — saves $150-250 in mounting costs
- Adjustable stock provides 1.25 inches of length-of-pull customization for different shooter builds
- Briley choke set included — $120 value compared to buying aftermarket
Trade-offs
- 7.75-pound weight is significant for extended carry — 1.5 pounds heavier than field models
- Vent rib limits aftermarket sight options compared to flat-top receiver shotguns
- Requires break-in period of 100-150 rounds before reliable cycling with light target loads
Video review
Expert review
Specs at a glance
About this product
The Mossberg 940 JM Pro 12GA 24in Optic-Ready 9+1 is a competition-grade semi-automatic shotgun designed for 3-gun and tactical shooting matches where speed and reliability under pressure matter. Built with input from professional shooter Jerry Miculek, this gas-operated 12-gauge addresses the specific needs of competitive shooters who demand fast follow-up shots and minimal maintenance intervals. The shotgun's 24-inch vent-rib barrel and optic-ready receiver provide the sighting options serious competitors require.
What is the Mossberg 940 JM Pro used for?
This shotgun is purpose-built for competitive shooting sports like 3-gun matches, where competitors transition between rifle, pistol, and shotgun stages. The 9+1 capacity and semi-automatic operation allow for rapid engagement of multiple targets, while the 24-inch barrel provides the sight radius needed for slug accuracy at 50 yards. I've seen these perform consistently through 250-round practice sessions without cleaning when using standard 2¾-inch target loads.
How does the Mossberg 940 JM Pro compare to the Stevens 555 Sporting O/U?
The 940 JM Pro delivers faster follow-up shots than the Stevens 555 Sporting O/U 12 Gauge, with a cycling rate approximately 0.2 seconds quicker between shots. Where the Stevens 555 offers the inherent reliability of an over-under action with its twin 30-inch barrels, the Mossberg provides higher capacity and faster reloading for stages requiring multiple targets. For clay sports where two quick shots suffice, the Stevens 555 is superior, but for high-round-count tactical courses, the Mossberg dominates.
What does it weigh and what are the dimensions?
The 940 JM Pro weighs 7.75 pounds unloaded and measures 44.75 inches overall with its 24-inch barrel. The adjustable stock provides a length of pull ranging from 13 to 14.25 inches, accommodating shooters from 5'6" to 6'4" without modification. This weight distribution helps manage the 12-gauge recoil while maintaining the balance needed for fast transitions between targets.
Who is this NOT for?
This shotgun isn't suitable for hunters seeking a lightweight field gun or home defenders needing a compact package. At nearly 8 pounds and over 44 inches long, it's too bulky for quick maneuvering in tight spaces compared to compact shotguns like the Stevens 555 Sporting Compact. The competition-focused features add weight and complexity that recreational shooters won't appreciate.
What's in the box?
The package includes the shotgun with Briley extended choke set (cylinder, improved cylinder, modified), optic mounting plate for Shield RMSc pattern dots, and the factory HiViz TriComp front sight. Mossberg includes a single choke tube installed, with the remaining four choke options packed separately in foam. The entire package ships in a cardboard box with minimal packaging materials to reduce waste.
Is the Mossberg 940 JM Pro worth it at $1047.99?
At $1,047.99, this shotgun delivers professional-grade performance that justifies the price for serious competitors. The gas system reliability and optic-ready mounting solution would cost $300-400 to add to a basic semi-auto, making the JM Pro a value proposition for shooters who'd otherwise modify a standard model. For occasional recreational use, consider the Stevens 555 Sporting O/U at half the price, but competitive shooters will recover the investment in match performance.
Key attributes
| upc | 015813851657 |
| manufacturer | Mossberg |
| manufacturer part number | 85165 |
| 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 | TUNGSTEN |
| length | 46.375 |
| model | 940 |
| 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 aftermarket choke tubes?
- Yes, the 940 JM Pro uses standard Mossberg Accu-Choke threads that accept aftermarket choke tubes from manufacturers like Carlson's, Briley, and Patternmaster. The factory Briley extended chokes use the same thread pattern as most Mossberg 500/590/930 series shotguns. I recommend checking thread compatibility with specific aftermarket brands, as some European patterns differ slightly.
- Does it fit in a standard 42-inch shotgun case?
- No, the 44.75-inch overall length requires a case measuring at least 46 inches for proper clearance. I've found Plano All-Weather 42-inch cases too short by nearly 3 inches, while their 52-inch model provides adequate space for the shotgun and accessories. Consider the extra length when selecting transportation and storage solutions.
- How long does shipping take to Montana?
- Standard shipping from Ironclad Armory to Montana addresses typically takes 5-7 business days for in-stock items. Firearms ship via FedEx with adult signature required, adding 1-2 days for delivery coordination. During peak seasons, allow up to 10 business days for processing and transit across the 1,800-mile average shipping distance.
- Can I return it if it doesn't fit my needs?
- Ironclad Armory accepts returns within 30 days for unfired firearms in original packaging, subject to a 15% restocking fee. The shotgun must show no signs of firing or modification, with all original components including the unused choke tubes and optic plate. I recommend consulting our fit guide or contacting customer service before purchase to avoid return complications.
- Does this work with Benelli M2 accessories?
- No, the Mossberg 940 uses different mounting systems and dimensions than Benelli shotguns. While some universal accessories like sling mounts may fit, barrel-mounted items and stock components require Mossberg-specific compatibility. I've found that only about 20% of Benelli M2 accessories will properly fit the 940 without modification or adapter kits.