American Rifleman | Assessment: Mossberg 940 JM Pro Shotgun

by B. Gil Horman –
Saturday 6th March 2021

When it comes to which product to buy next, there is nothing more magical than a celebrity recommendation. A famous face or name will grab our attention and direct our attention all the way to the cash register. But when we are honest with ourselves, not all endorsements are created equal. Just because a famous person’s name is linked to a particular item doesn’t mean they were involved in its development, or even use it in real life. Mossberg’s 940 JM Pro shotgun is different.

The JM in the name is an abbreviation for world champion competition shooter Jerry Miculek and his family, who are also world-class competitors. Like others participating in three-weapon games, the Miculeks realized that Mossberg’s 930 JM Pro series was a huge step in the right direction. But a few more tweaks were needed to find the right weapon competitors. The gas system of the 930 is a little too tight for working with racing guns.

The left side of the Mossberg 940 JM Pro.

It needs to be cleaned approximately every 600 laps. That’s plenty of room for hunting and athletic clays, but three-gunners tend to throw a lot more grenades than the average athlete. More precautions also had to be taken to adjust the shoulder stick to better fit the shooter who is using it. Mossberg used the 930 JM Pro-Series shotgun as a starting point to work with Mr. Miculek and his family to take this semi-automatic series to the next level.

Applying family input and extensive shooting experience resulted in a variety of modifications and improvements, including changes to the sighting system, gas system, controls, and bearing configuration. The goal was to incorporate a whole bunch of features to give three gunners a tricky, ready-to-use 12-ga. Ready to use out of the box for less than the cost of a bespoke weapon.

A look at one of the chokes, ventilated rib, and front fiberglass bead on the Mossberg 940 JM Pro.

A look at one of the chokes, ventilated rib, and front fiberglass bead on the Mossberg 940 JM Pro.

The 940 JM Pro series was launched with two 24-inch barrel models. The version shown here (No. 85111) has a three-color finish with a matt blued barrel, black polymer shafts and a tungsten gray receiver made of anodized aluminum. The bolt handle, the bolt release button, the trigger and the safety slide are all provided with a clearly visible gold-colored anodized finish. The other finish option (# 85113) includes a black receiver and controls with a set of black MultiCam camouflage shafts.

Some of the key changes to the 940 are hidden in the gun. Internal components have been treated with a nickel-boron finish to increase lubricity and make cleaning easier. The gas system has been redesigned to run faster and more reliably on a variety of 2 ¾ “and 3” 12-ga. Grenades shot. This system includes a tiered and ventilated spacer component that releases moisture and dirt with every shot. This system successfully reduces maintenance time by firing up to 1,500 rounds instead of around 600 between cleanings.

A closer look at the Mossberg 940 JM Pro action.

A closer look at the Mossberg 940 JM Pro action.

Another subtle but important change concerns the return spring system. Due to the shortening, this shotgun could be fitted with an adjustable synthetic shoulder stick. It comes with a full set of handle and recoil pad standoffs that allow the case and throw to move between 13 “and 14.25” along with the pull length.

The 24-inch barrel is the product of a new manufacturing process developed by Mossberg to aid in more accurate shot placement when using factory-made ammunition. The barrel has a ventilated rib and a fiber optic HIVIZ TriComp visor. The 940 arrived with a triangular green visor along with an additional set of interchangeable red, green, and opaque white visor pins of various shapes and sizes.

The butt of the Mossberg 940 JM Pro.

The butt of the Mossberg 940 JM Pro.

The muzzle is threaded to accept Mossberg’s Accu-Chokes. This model comes with a set of three extended Briley throttles including a cylinder, upgraded cylinder, and modified options with a plastic case for storage. The extended aluminum magazine tube has a threaded cap and a knurled aluminum connector that makes it easy to disassemble for cleaning. The magazine holds up to nine 2 ¾ “trays with one in the chamber.

This shotgun has been designed with a set of slim profile stocks, the texture of which is sculpted along the front piece and handle to enhance the purchase. The front part has a short, curved extension that complements and protects the receiver on the charging port. The shoulder stick is covered with a softly structured rubber recoil pad that cushions the shoulder well against felt recoil.

A right side view of the Mossberg 940 JM Pro.

A right side view of the Mossberg 940 JM Pro.

At the heart of the 940 JM Pro is a durable aluminum receiver with a grooved top that has been drilled and threaded for a scope mount. This function is useful for those who want to attach a red dot optic. You won’t find a polymer used in and around the recipient. All controls are made of aluminum, as is the trigger housing. The latch handle and latch release button, both located on the right side of the receiver, are oversized with a stylized texture. The safety slide mounted on the spigot is easy to use for right or left-handers.

The beveled charging port, bright orange aluminum magazine holder, and shell lift have all been configured for quick reloads, including quad loads. Inside the rounded trigger guard there is a small pin that serves as a visible and tactile cocked hammer indicator. The pin retracts into the trigger guard to indicate that the bolt must be turned to reset the hammer. The one-step, smooth-surfaced print showed a clean 4 pound break. 13-oz. pull the trigger.

The Fiocchi USA 12-ga.  Ammunition used for testing.

The Fiocchi USA 12-ga. Ammunition used for testing.

On the track, the 940 JM Pro’s handling turned out to be as good as I’d hoped. It ran flawlessly with all 2 2 “rounds tested. Most of the shells fired were Fiocchi USA high-speed bird-shot charges that fired size 7.5 lead pellets at a stated speed of 1,330 fps. This charge is heavy for a competition platform, but the gun’s action and recoil pad soaked up the recoil from the felt well.A sample test at 20 meters using a grease board and the modified size choke provided showed that the pattern fit comfortably within the 30-inch diameter ring of the board.

The Mossberg 940 JM Pro 12-ga. The three-gun shotgun is a ready-to-use competition platform for experienced contestants or those new to the sport who want to skip an expensive trip to the gunsmith. This shotgun is quick to load, quick to use, and fun to work with. In fact, it won the NASGW / POMA 2020 Caliber Award for Best New Shotgun. It would be a shame to keep all of the enhancements that the 940 represents for the three-gun competition only, as many of them would be useful for other purposes as well. Fortunately, that won’t be the case. The JM Pro version of the 940 is just the first in a line that will include field and defensive models.


Manufacturer: OF Mossberg & Sons

Model: 940 JM Pro (No. 85111)

Measure: Gas-powered half car

Caliber: 12-ga., 2 ¾ “and 3” shells

Receiver: Hard anodized aluminum, drilled and threaded for the optics

Barrel: 24 “ventilated rib, smooth bore

Magazine: tubular, matt black aluminum with extension

Visor: HIVIZ fiberglass, interchangeable

Trigger: Smooth aluminum arch

Trigger guard: aluminum

Safety: Tang-Mounted Slider, Metallic

Front end: Checkered black polymer

Shoulder shaft: Checkered black polymer

Recoil pad: Textured and ventilated black rubber

Drop at Comb: 1.35 “

Drop at Heel: 2.15 “

Draw length: Adjustable, 13 “-14.25” with included spacers

Choke: Interchangeable Briley Extended, M and IC provided

Overall Length: 44.75 “

Trigger: 4 lbs. 13-oz. (as tested)

Weight: 7 pounds. 11 ounces, unloaded

Magazine capacity: 9 + 1 use of 2 ¾ “shot cartridges

Accessories: 3-throttle set with case, standard spacer set, visor light guide set, lock, operating instructions

MSRP: $ 1,078

Comments are closed.