The Mossberg 590R Stand Off

Since the first Mossberg 500 appeared in August of 1961, over 11 million guns later it’s become the most-produced shotgun in history. Driven in part by the adaptability offered by its tool-less barrel change, it has evolved continuously and welcomed the 590 and unique Shockwave into the family.

Introduced in 1987 and promptly adopted by the U.S. Marine Corps, the military-focused 590 is built on the M500 with a bayonet mount and modified magazine tube allowing the gun hold up to nine rounds. According to Mossberg, at the time it was the only pump shotgun to meet military specifications that required no more than three malfunctions in 3,000 rounds of 00 buckshot.

All-Around Goodness

The 590 was used in the Global War on Terror, often for breaching doors, and is popular for home defense. It also remains in law enforcement use where less-lethal and other applications keep the shotgun relevant. If you’re wondering which of these roles the 590R is best suited for, the answer is “yes.”

The heart of the 590R is familiar and proven, while the controls distinguish it. Mossberg was the first to put the safety on top on a pump guns where the lines of a traditional stock make it easy to locate with either hand. What it’s not is like anything else you shoot or a good match for pistol-grip stocks.

The thumb-activated selector, as on the AR, is the gold standard for a go-bang switch and a welcome addition to the 590R. The “R” is for the AR-style rotary safety, which has ambidextrous levers located where your thumb is used to finding them.

The 500/590 bolt release is a small, narrow tab on the left side of the gun that’s hard to find in a hurry. The 590R, however, has an extended contact pad located where it’s easily hit with the top of your thumb. It also comes with an M4-style collapsible buttstock and Magpul MOE pistol grip, which are easily replaced with standard AR parts if you have other preferences — in my case, the Ergo pistol grip and Magpul CTR. The stock’s locking surfaces on the polymer extension are steel-reinforced, which is reassuring, considering the 12’s storied recoil.

The rear of the gun has five QD sling cups, three on the stock, two on the extension, with a removable mount on the front with a single M-Lok slot per side. I’d be afraid to use it for a light because it’s gonna catch a lot of blast so close to the muzzle, but it’s perfect for a sling mount.

Trial and Bloody Error

I shot a 590R prototype at Gunsite a couple years ago and was duly impressed. As a longtime shooter of 1911s and ARs, my right thumb expects to do something when I pick up a gun, and the rotating safety fit the bill beautifully. My only complaint was a sharp edge I found on the pump, which I casually mentioned while wiping the blood off. The engineers didn’t just write that down — it’s gone!

The pump design itself mimics the profile of Mossberg’s earlier Bullpup 12, with shelves front and rear to keep your hand in place. Crosswise slots on either end of the pump provide mounting surfaces for a strap, should you be so inclined. Deep grooves provide a sure grip, and the lines are echoed in the cooling slots of the steel heat shield.

Heat shields date to WWI when Winchester’s ’97 trench gun, the great-grandaddy of them all, had one added so soldiers could use the bayonet without burning their hands. They also look ridiculously cool and have been a regular feature on Mossberg for at least 40 years. Typically, they’re clamped around the barrel by screws augmented by a plastic spacer. The 590R’s more-secure mounting system has the shield mate with a steel boss on the top of the barrel where it’s held into place with a screw. Hold that thought.

Two tube-fed versions of the 590R are currently available including the Stand-Off model covered here. The sharp breacher muzzle is intended to bite into a door frame to blow it open, and the vents and opened-up bore provide a safe escape for propulsion gas so the barrel doesn’t explode if the shot hits the door before clearing the muzzle. There’s little application for it in the civilian world, just like there’s little reason to hit or stab someone with your shotgun since a gun grab is generally justification for lethal force. All that said, absolutes are few and the sharp end with a couple hundred pounds of homeowner behind it could be a very effective tool for a multitude of purposes

List prices hover around a grand, with magazine-fed models a bit more. All come with a Picatinny rail, while the standard model adds a set of flip-up backup iron sights.

Sights and Patterning

I used Trijicon’s MRO-HD 1×25 optic during the test. While tall, the QD mount aligns it correctly for the gun’s ergonomics. Powered by a single 2032 battery and boasting 2.5 years runtime for the dot setting, it has 16 brightness settings and a choice between a simple 2 MOA dot or a segmented circle which reduces runtime to 75 days. Generally, I prefer a simple dot until I noticed the MRO’s circle is 68 MOA. Like anything else in MOA, it covers an increasingly large area of the target the further away it gets … not unlike a shotgun pattern.

At 10 yards, the 590R put 9-pellet 00 buckshot into an average of a little over 7-1/2″, not far from the 6.8″ the circle reticle represents at that range. Similarly, the ring covers 17″ at 25 yards, where the 590 averaged 19″ patterns. Seven yards is close to the spread at 4.7″, making me think there’s merit in using the ring as a rough approximation of where the pattern will hit.

Still, I like iron sights, at least as a backup and the 8/32 heat shield screw proved an irresistible temptation. XS Sights provided a tritium dot front sight for an AR, which is threaded at 8/36. I rethreaded it to 8/32, shortened it with a file and screwed it in place; now I have a front night sight. One hopes Mossberg will consider swapping thread pitch for those who want a front sight without doing their own blacksmithing. Shotgun cards from Ibex Applications rounded out the limited modifications I made to the gun, and it was time for the range.

Throwing Down

The 590R was a bit sticky at first, with a couple failures to extract in the first box of shells. Using the “hellacious rack” Gunsite taught me to give a pump gun, it quickly smoothed out and there were no more malfunctions of any kind.

“Comfortable” and “12 gauge” don’t really belong in the same sentence, but the 590R is not unpleasant to shoot with the vented breacher muzzle acting as a brake. A hundred rounds of buck and slugs with the well-padded factory buttstock left my shoulder with nary a mark.

The flat trigger breaks at an average of 5 lbs., 9 oz., with the least creep I can still feel. I love the thumb safety, though I found it easier to reapply with my trigger finger. The squarish front of the trigger guard made twin loads a little awkward because of the angle at which the shells need be held to keep them lined up, but the port itself is nicely relieved, and I learned to manage it. My best split times for two rounds were .35 seconds.

I fired over 300 rounds, including 100 rounds of Winchester Universal #8 birdshot, slugs and 00 buckshot provided by Federal and Sellier & Bellot, #1 buckshot from Fiocchi and, with less-lethal in mind, a rubber ball load from S&B. Lightweight projectiles shed velocity quickly, and accuracy with it. The rubber ball load went into 3-1/2″ or so at 15 yards but over twice that at a mere ten yards more. I’m sure it would still sting, wherever it hit.

I measure shotgun patterns with a tape measure rather than a dial caliper, but on average the 590R put nine 00 pellets into just under 4.73″ at 7 yards, 7.63″ at 10, 11.67″ at 15 and 19″ at 25 yards — note that all of these are well under the old trope of one-inch-per-yard, which in my experience simply doesn’t hold true for buckshot.

Slugs were brilliant, with five of S&B’s one-ounce Special Slug Sport going into about 2 1/2″ at 50 yards, and when I shot steel from 100 yards, there was no mistaking a hit.

The shotgun is a thinking-man’s weapon. Misunderstood and often difficult to manage, it does what it has always done, which is deliver a fight-stopping payload unmatched by other defensive firearms. Mossberg’s 590R makes it much easier to deliver that power with the familiar controls and furniture of the AR platform, which is a major improvement for both seasoned shotgunners and those new to platform.

Mossberg.com

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