Mossberg M590A1 Special Purpose

mossberg_logoThe Mossberg M590A1 Special Purpose has been on my radar for a number of years, not that I needed another shotgun. However, the Mossberg M590A1 Special Purpose was the last in my bucket list of modern firearms. Today, the bucket list was filled.

Mossberg M590A1 Special Purpose

Mossberg M590A1 Special Purpose

The 590A1 was first introduced in 1980s. Born from the 500 series that appeared in 1960, it has, at the U.S. Navy’s request, a heavy-walled barrel, metal trigger guard and safety, and a new corrosion-resistant finish. The 590A1 was adopted by the U.S. Army, Navy, Coast Guard and several Special Forces units and has since been issued by several hundred police departments, as well as state and federal agencies including the NYPD and the Texas Department of Public Safety.

The primary purpose of the Mossberg M590A1 Special Purpose is to deter and defend. The M590A1 Special Purpose is quite capable of doing both. The M590A1 comes in many configurations and after perusing the choices, doing some homework, and watching some videos, a version was finally chosen and the specifications for it are shown below.

Mossberg M590A1 Special Purpose Specifications

Mossberg M590A1 Special Purpose Specifications

The first thing that is noticeable when hoisting the beast is the weight; this is not you granddaddy’s bird gun. At 7.25 pounds, it weighs slightly more than the Ruger Gunsite Scout but less than the Springfield M1A and about one pound more than your standard Mossberg 500. It is very well built, operates smoothly and it has good fit and finish. Since this model was built for military use in difficult environments, everything about this shotgun seems to focus on reliability–the weapons ability to function despite environment or abuse.

Sight Choice:

Rear 'Ghost' Sight. Note Center Alignment Marks.

Rear ‘Ghost’ Sight. Note Center Alignment Marks.

I chose the version that has a rear ghost sight with a ramped front sight. The front sight has a high-visibility florescent orange stripe down its center and is brazed onto the barrel and picks up quickly in the rear sight. The front sight is drift-adjustable for the x-axis (horizontal – windage). I did notice slight sloppiness in the application of brazing on the front sight to the barrel. A little cleaning and a tube of Testors Flat Black enamel paint cleaned that up.

The rear sight’s large aperture (.211 inches) is definitely made for close work and provides a full field of view when sighted with both eyes open. The rear sight is y-axis (vertical – elevation) adjustable and firmly bolted to the top of the receiver. Twin ears protect the rear sight from damage. In addition, there is center indicators painted on each side of the rear aperture for lining up the front sight.

Barrel and Action:

This is 'The End' that Does the Business.

This is ‘The End’ that Does the Business.

The heavily Parkarized barrel’s thickness is impressive and one should be able to thrust 1-ounce slugs downrange as long as the shoulder will let him. The M590A1 runs both 2.75-inch and 3-inch shells and is robust (more than my shoulder) enough to run those 3-inch magnum shells with authority. With a 20-inch, .73 caliber barrel (that’s 18.5 mm for those who prefer the metric system) whatever is downrange is not going to hold up well under fire from this thing.

The nine-shot capacity feed tube provides enough fodder (9 + 1 rounds of 2.75-inch shells) for the M590A1 to add a half-pound of lead weight to a bad guys diet in one sitting.

The fore end is molded into the Twin action bars. Since the shotgun is new, the action is slightly stiff but will loosen up after use. The fore arm rattles but that is the nature of slide-action shotguns. Unlike most Mossberg shotguns; however, the trigger guard is metal and is large enough for gloved hands.

The slide release is on in the lower left side of the receiver. Since I shoot Long guns left-handed, it is a good position for the trigger finger. For a right-handed 590A1 operator, the thumb would actuate the slide release.

The trigger is heavy and breaks around 7.5 pounds. There is a light amount of take-up and a slight amount of over-travel. The trigger itself breaks crisply but no overly so. It is a combat trigger and the 590A1 is not a target rifle, after all.

The Safety is Just where I Like It - Centered

The Safety is Just where I Like It – Centered

The metal safety is located in my favorite place – top center. The safety is stiff and just the way I like one to be; there is no knocking it into safe mode unless you want it there.

Stock and Forearm:
The stock is, of course, synthetic. I had the option of obtaining a version with shell storage in the stock and rails on the forearm for attaching stuff, but I passed it up. A simple stock and forearm are more than adequate for me. No sidesaddle for this one, I have a butt-stock pouch that will take care of my reloading needs. The butt-stock has a nicely textured grip and a firm, tacky recoil pad. The LOP on this particular version is 14-inches. Normally, I would add a recoil pad to get the LOP to my preferred 4.25-inch LOP, and still may do so depending on how the shotgun performs with me.

Fit and Finish:
With the exception of sloppiness in brazing of the front sight, the fit and finish is excellent on this model. This is, after all, going to be a working shotgun – it is not a pretty boy nor was it ever intended to be.


Mossberg M590A1 Special Purpose

Mossberg M590A1 Special Purpose

Some may question the virtue of have a 20-inch barreled shotgun for defensive use, and while I will agree that the extra barrel length make the shotgun a little more unwieldy, it is simply not that much of an issue – the extra barrel length is not going to impede someone who can run a shotgun properly. The Mossberg 590A1 Special Purpose is a special purpose shotgun that is made to withstand the rigors of combat or field use. It has successfully performed worldwide and that should say something. The effect of a longer barrel is greater velocity and range for slugs at medium distances and tighter patterns of #00 and #4 buckshot at closer distances. Plus, having 9-rounds in the tube doesn’t hurt either.

For giggles, I may add a heat shield, sling, and M7 bayonet system for it but for all intensive purposes, the Mossberg M590A1 Special Purpose will fulfill its purpose without those things – deter and defend.

I’ll do a follow-up range report at some time in the near future.

To learn more about the Mossberg M590A1 Special Purpose shotgun, go to:

To watch Hickock45 run the Mossberg 590A1 (not Special Purpose) shotgun, go to (a different version than mine (I did not get the bayonet either) and


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About Taurian

Taurian is a U.S. Army veteran and former LEO and Defensive Tactics Instructor. Taurian also has over fifty years of experience as a Technical Writer and Training Program Developer. After leaving home at the age of ten without any shoes, Taurian continues on with many years devoted to the keeping and bearing of arms.

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