At 20 yards and shooting offhand, the Mossberg 590RM Magazine-Fed pump action laid in slugs nearly on top of each other. The 00 buckshot loads were threat stoppers at this distance too, the eight- and nine-pellet loads solidly whacking the center mass of my silhouette targets. Closer and the buckshot formed fist-sized groups.

Meanwhile the 12-gauge’s trigger snapped off very cleanly, much better than most shoguns I’ve used. The pump action worked smoothly, and the detachable magazine fed shells fast and easy. 

Built for the law enforcement, tactical and home defense users, the 590RM offers   substantial and accurate firepower, and does so in a rugged build made to work in tough conditions. The well-thought-out detachable magazine design functioned extremely well in my test shooting, though the large size of the magazines does represent a potential challenge.

New Platform

In January 2025, O.F. Mossberg & Sons, Inc., introduced the 590R and 590RM (Mag Fed) 12-gauge shotguns featuring Mossberg’s ambidextrous rotary safety selector plus AR-style ergonomics. The four models included two standard offerings, the 590Rs, and two magazine-fed versions with the “RM” designation. The latter employed the first production double-stack magazines for pump-action shotguns.

Shared features of these 590 platforms included non-binding twin action bars, positive steel-to-steel lock-up and anti-jam elevator, and dual extractors. 

My test and evaluation 590RM Mag Fed shotgun featured the detachable magazine’s integral stabilizing ribs that engaged the magazine directly to notches engineered into the receiver for a very positive lock-up. The lever-style magazine release button was positioned in front of the trigger guard for ambidextrous access. 

The 590RM also featured an 18.5-inch barrel with integrated heat shield, a compact forend, a 5-position adjustable stock with interchangeable recoil pad, and an MOE pistol grip. The Picatinny rail on the receiver made for easy mounting of optics. 

Front and rear Mapgul MBUS 3 sights rounded out the package. The shotgun sells with a 10-round magazine and 5-, 10-, 15-, and 20-round mags are available as additional purchases.

My 590RM, SKU 50213, includes an AccuChoke-compatible barrel, with Cylinder choke tube included. 

There is a second 590RM available, too, SKU 50218, essentially the same as my model but featuring a stand-off attachment at the end of the barrel.

In Sight

I first ran my Mossberg using the Magpul MBUS 3 Adjustable open sights.  They worked fine, up close. But even with the larger rear peep option, things got blurry for me past 10 yards. That’s not a critique of the sights at all, but the reality of my aging eyes.

To find out what the 590RM was capable of, I needed an optic, and I chose the Meprolight M22 Pro. This reflex sight operates in daylight using fiber-optic illumination and also employs tritium vials for nighttime work. A single CR2032 battery runs a factory installed power module to add reticle illumination when you experience washout.

The M22 Pro featured a height-over-bore at 1.5 inches, with elevation and windage controls operating at 1 MOA per click. The generous display window (1.0-inches by .80-inches) really made the optic’s 3.5/40 MOA amber reticle pop. The Picatinny rail quick release (MIL-STD 1913) mount easily attached to the shotgun’s rail, and the optic height was such that the folded down open sights were not visible.

On Target

My goal was to run the 590RM hard, and that I accomplished using a substantial selection of 12-gauge ammunition.

For shotshells, I used:

--Federal Premium FORCE X2, 9-pellet 00 buckshot.

--Hornady Critical Defense, 8-pellet 00 buckshot.

--Remington Ultimate Defense, Managed Recoil, 8-pellet 00 buckshot

And for slugs:

--Fiocchi EXACTA Aero-Slug, 1 ounce.

--Remington AccuTip, 385 grains.

--Remington Slugger, 1 ounce. 

--Winchester Razorback XT, 1 1/8 ounce.  

I first zeroed the 590RM and the M22 Pro using Remington AccuTip slugs at 20 yards shooting from a rest. My first two shots were approximately 6 inches low and 2 inches to the right. It took many clicks of the M22’s controls but only four shots to put me on the bullseye.

Confident in my zero, I switched to the buckshot loads starting with the Remington Ultimate Defense. At 10 yards, the shooting proved too easy, with all eight pellet holes covered by the palm of my hand.

I backed up to 15 and 20 yards, and patterns got wider. But the 590RM and that double stack magazine are designed to provide some fast and furious shooting, not a slow and deliberate shot or two.

I loaded up with the Hornady Critical defense and fired off quick, three-shot strings into the center mass of Caldwell LE Silhouette life-sized targets. At 15 yards, the Hornady just eviscerated the center of my targets.

And at 20 yards, three shells worth of the Federal Force X2 and the Remington Ultimate Defense would stop any threat, hard. 

Slugs were next on the schedule. 

To test out the slugs plus the magazine’s function, I loaded magazines with a four-slug load, alternating brands so they fired off in this order: Fiocchi, Remington Slugger, Winchester Razorback, and Remington AccuTip.

I shot from 15 yards offhand at black triangles drawn onto cardboard with a thick marker. The different brands of shells racked into and out of the shotgun chamber  smoothly, while I actually made some tighter groups.

I ended my slug fest with three of the Fiocchi’s aimed at the nogging of a Caldwell target. They slammed in at just over 2 inches, with two of the three slug holes touching. 

Impressive rig.

Smooth Operator

The three metal tabs (Mossberg terms them “stabilizing ribs) along the left and right top edges of the 590RM magazines meshed perfectly and very solidly with the three cuts on the mag well. So perfectly, inserting or removing the magazine with one hand was easy to accomplish.

But the 10-round magazine is large and wide. Inserted, the 10-round magazine protrudes 7 inches below the receiver and 3 inches beyond the pistol grip. The 15- and 20-round magazines are even longer. In tight situations (firing from a vehicle, for example) the magazines could really get in the way.  

Still, when lots of quickly delivered firepower is needed, it’s hard to beat the 10-round mag, as well as the also available 15- and 20-rounders. And a shorter 5-round magazine is also an option for scenarios in limited spaces.  

The shotgun’s trigger broke at 2 pounds, 10 ounces on average, and it broke crisply.  Actually, this is the best trigger I’ve ever used on a tactical shotgun, and in fact beats out a good number of rifle triggers.

The shotgun’s pump action was initially stiff, but a little lubrication and racking a dozen shells through smoothed out the action.

AR Customers

Your 590RM customers may well be your past and current AR-15 customers.

“The 590RM and the 590R are designed for the serious shooter interested in a home defense and/or a tactical shotgun that has similar grip, safety controls and sighting options to that of an AR-15 style rifle,” said Richard Kirk, Mossberg’s senior director of marketing.

Kirk suggested that sales staff introduce the 590RM by pointing out these AR-like features including the Picatinny rail designed for the AR-15 red-dot-style optics. Point out the 5-position, Mil-Spec butt stock, too.

“The shotgun’s ambi rotary safety selector switch is very similar to safety switches found on the AR-15s, too” Kirk added. “Similar to that of an AR-15, where there is no need to break the grip to operate the safety [on the 590RM] unlike other Mossberg pistol-grip-equipped shotguns where the safety selector switch is located on the top of the rear of the receiver.”

Of course, the ammunition capacity deserves attention as well as the other magazines available (creating additional purchase possibilities).

For display, consider showing off a 590RM positioned horizontally, with an optic mounted on the shotgun and the 10-round magazine in place. It will grab customers’ attention.

Sales Help

In store, Mossberg regional sales managers can supply sales staff training. At this time, the gun maker does not offer co-op or spiff programs. 

“Mossberg does not sell directly to independent dealers,” Kirk noted  “All sales of Mossberg products must be done through a distributor or buy group. And Mossberg  products are available through all major distributors.”

To become a Mossberg dealer, all an FFL needs to do is buy Mossberg products for resale through a distributor or buy group. Once they are offering Mossberg, FFLs can send a request to have their dealer information added to the Mossberg website by sending an email to  marketing@mossberg.com.

The 590RM is featured in magazine articles by all major firearm consumer and industry publications. Content has also been developed by most major firearm-specific YouTube and social media channels.