The Mossberg 940 JM Pro is a 12-gauge semi-automatic shotgun developed with input from competitive shooter Jerry Miculek. It has a 24-inch barrel, 9+1 round capacity, and weighs 7.8 lbs at 44.8 inches overall. The adjustable synthetic stock runs from 13 to 14.25 inches length of pull. Finish is matte blue. 
 

Key Specifications 

• Brand: Mossberg 
• Model Name: 940 JM Pro 
• Gauge: 12 
• Chamber: 3" 
• Action: Semi-Automatic 
• Capacity: 9+1 rounds 
• Barrel Length: 24" 
• Overall Length: 44.8" 
• Weight: 7.8 lbs 
• Sights: Fiber Optic Front Sight 
• Stock Material: Adjustable Synthetic Black 
• Trigger Type: Standard 
• Finish: Matte Blue 
   

Detailed Features 

1. The adjustable stock (13"-14.25" LOP) accommodates different shooter builds without aftermarket parts. 
    
2. Fiber optic front sight gives quick acquisition in varying light. 
    
3. The Briley extended choke system includes IC, Cylinder, and Modified chokes for different target distances and patterns. 
    
4. The enlarged loading port speeds up reloads under competition pressure. 
    
5. The oversized charging handle is accessible with gloves or in adverse conditions. 
    
6. A two-position thumb safety is easy to engage or disengage without breaking grip. 
    

Target Audience 

Primarily built for competitive shooters in sporting clays and three-gun matches who need fast cycling and a reliable semi-auto platform. Also works for hunters who want the flexibility to adapt choke selection to different game and conditions. 
 

Usage Scenarios 

1. Competitive shooting: quick follow-up shots and the enlarged loading port give a real advantage in timed events. 
    
2. Home defense: 9+1 capacity and semi-auto action are practical for defensive use. 
    
3. Field hunting: interchangeable chokes adapt the pattern for waterfowl or upland birds. 
    
4. Recreational range use: the adjustable stock and manageable recoil make it accessible for varied users.

The Mossberg 940 JM Pro gets strong marks for competition use, with some practical considerations around maintenance and price.

Most users highlight reliability in competitive settings. The semi-auto action cycles smoothly with various ammunition, which matters for three-gun and sporting clays where misfeeds cost time. Ergonomics draw consistent praise: the adjustable stock, well-placed controls, and overall balance make it comfortable for long range sessions. The fiber optic sight and choke flexibility are called out as genuinely useful rather than checkboxes.

The black and tungsten color scheme is well-received aesthetically. Users interested in accessory customization find the platform accommodating for optics and other add-ons.

The main criticisms: pricing sits higher than some expect for a production semi-auto shotgun, though most who've shot it consider the performance worth the cost. Maintenance comes up as a consideration, since the semi-auto mechanism requires more cleaning attention than a pump-action, particularly after extended use with lighter loads. Recoil management is generally rated positively, with the design helping keep the gun on target during rapid strings. Mossberg customer service experiences vary among users.