Tested: Mossberg Retrograde 590A1

posted on October 2, 2019

Those of us working in the shooting industry see gun manufacturing ventures come and go, some of which seem to spring up and then vanish over night. So, it's quite gratifying to see an American manufacturer like Mossberg reach its 100-year anniversary. One of the ways the company is celebrating this milestone is with the release of the Retrograde series of 12-gauge pump-action shotguns. The model that immediately caught my attention at the 2019 SHOT Show (and that of many other attendants) was the 590A1 Retrograde, which is a modern interpretation of the classic “trench gun.” But before we dive into the review, here's a bit of background on this new model.

In the early 1960s, the shooting community witnessed the rise of Mossberg's 500 series of 12-ga. shotguns. Among the most popular pump-actions in the United States for shooting sports and home defense, the company now boasts more than 100 models in the 500 line-up chambered for a variety of shot shell sizes. Included in this series are the tactical 590 and 590A1 models, which have been specialized for law enforcement and military applications. In fact, since 1979, the 590A1s are the only pump-action shotguns to pass all of the U.S. military’s stringent 3443 specification requirements which include a 3,000-round endurance test.

Image courtesy rockislandauction.com

Nearly half a century before the 590A1 was developed, the leaders of the U.S. Armed Forces realized that American soldiers needed a potent, close-range weapon when enemy combatants charged into the narrow confines of the trenches along the western front during World War I. The Winchester Model 1897 was pressed into service and, with a few modifications, became the M1897 trench gun. It sported a shorter 20" cylinder bore barrel, a perforated heat shield to protect the operator's hands, and a bayonet lug. Loaded with six shells of .33-cal. buckshot, this dependable pump-action scattergun gave soldiers and marines the close-quarters advantage they needed. 

As a tribute to the World War I trench gun, the 590A1 Retrograde has been decked out with key features reminiscent of the M1897. The classic walnut furniture includes a “corn cob” fore-end and a shoulder stock with a checkered grip. The vented and textured rubber recoil pad is made of brown rubber to better match the dark finish of the walnut stocks. The 20" heavy-walled barrel, which has a fixed cylinder bore choke, is topped with an M1897 type ventilated heat shield. The barrel, magazine tube, magazine cap, twin action bars and heat shield have all been treated with a matte black Parkerized finish. Last, but certainly not least, is the bayonet lug. Although this shot gun will not accept the original 17" blade Winchester 1917 bayonet (which also fit the U.S. M1917 Enfield .30 caliber rifle) it can be fitted with an M-16 type bayonet should you choose to attach one. 



This version of the 590A1 is topped with an excellent set of adjustable ghost ring sights. The front sight blade is blaze orange and the rear sight is shielded and fully adjustable. The aluminum receiver is treated with a matte black, hard anodized finish. While the sporting 500 models often ship with polymer trigger guards and tang-mounted safety sliders, the 590A1 has an aluminum trigger guard and all of the external controls are metallic. The trigger pull was a smooth 8 lbs. 1 oz., according to a Lyman's digital trigger gauge.

Folks who've been keeping an eye on ammunition trends will have noticed a spike in demand for 1¾" mini 12-ga. shotgun shells (the majority of 12-ga. shells are between 2¾" to 3" in length). This is due largely in part to the popularity of another Mossberg product, the non-NFA 590 Shockwave firearm released in 2017.

Because the Shockwave has a 14" barrel instead of an 18.5" or 20" barrel, its abbreviated magazine tube holds five rounds of 2¾" shells instead of the more tactically advantageous eight rounds of longer models. Switching over to 1¾" mini shells brings the magazine capacity back up from five to eight rounds. In a 20" barrel model like the 590A1, the eight-round magazine will hold 12 mini shells. These shorter rounds also tend to produce less felt recoil which in turn improves shooting comfort and control.

To ensure proper feeding with 1¾" shells in Mossberg 12-ga. pump actions, OPSol Texas offers the affordable Mini-Clip. For this review, I worked with the latest version, the 2.0 Flex. It's a wedge-shaped rubber block that fits Mossberg 500, 590, 590A1 and Maverick 88 models. The Mini-Clip acts as a buffer to position the Mini Shells in just the right spot to chamber properly as they move from the magazine to the elevator assembly. You just press it into the opening in the underside of the receiver nearest the shoulder stock. It can be installed and removed manually, no tools required. If you want to fire 2¾" or 3" shells, just pull the Mini-Clip out of the receiver.

Although Aguila Minishells used to be about the only option for short-shell shucking, other companies are quickly getting on board. This year Brownells became the exclusive American distributor for Challenger Ammunition's 1¾" Super Short Shells, which are manufactured in Canada. Brownells currently offers two Super Short loads including a 5/8-oz. #7½ lead birdshot round and a 14-pellet #4 Buckshot load. Both shells have a listed velocity of 1200-fps. The shells I worked with were neat, clean and well made. They functioned flawlessly in the Mossberg 590A1 when the Mini-Clip was installed in the receiver. At $6.99 per 20-round box, they are half the price of the Aguila offerings but, as of this writing, there's not a slug load available in the Challenger line up.

The ammunition used to test the 590A1 Retrograde included a mix of 1¾" and 2¾" 12-ga. shells including inexpensive birdshot, defensive buckshot and slug loads. The shotgun cycled all of them smoothly and reliably without any mechanical or ammunition related malfunctions. Although synthetic materials are handy for a variety of gun stock applications, I have to admit that nothing else provides the look and feel of a quality set of walnut stocks. And if you've never used a set of adjustable ghost ring sights on a tactical scattergun and don't get what all the hype is about, trust me, they're terrific to work with for this type of shotgun.


Once I had a feel for the gun and its reliability, I checked the pattern of the cylinder bore barrel at 10 yards (which reflects performance at across-the-room distances) using Birchwood Casey 12"x18" Shoot-N-C targets. Loading the 590A1 with nine rounds of Hornday's American Gunner 1-oz. Reduced Recoil Rifled Slugs (#86231) produced a ragged 2.25" hole in the target.

The Challenger Super Short #7½ birdshot load produced a 15" pattern that covered most of the target while the 14-pellet #4 buckshot printed a 7" pattern.

At times, the new gun market can get a bit bland. There's an awful lot of black polymer out there these days. The Mossberg 590A1 Retrograde is a refreshing change of pace. It sports the classic appearance and walnut stocks of a vintage collector’s item but is, by no means, a safe weight. Loaded with tactical features and built to last, this Mossberg pump action is a fully functional, ready-to-work defensive shotgun for on-duty or home defense applications. 

Shotgun Manufacturer: O.F. Mossberg & Sons
Model: 590A1 Retrograde (#51665)
Action: Pump Action
Caliber: 12-ga., 2 ¾” and 3” Shells
Receiver: Hard-Anodized Aluminum
Barrel: Heavy Walled, Matte Black Parkerized with Heat Shield
Bayonet Lug: Yes
Magazine: Tubular, Matte Black Parkerized
Front Sight: Dovetail Blade with Orange Enamel
Rear Sight: Adjustable Ghost Ring
Trigger: Smooth-faced steel bow
Trigger Guard: Aluminum
Safety: Tang-Mounted Slider, Metallic
Fore-end: Ribbed Walnut
Shoulder Stock: Walnut with Checkered Grip
Recoil Pad: Textured and Vented Brown Rubber
Sling Swivel Studs: Yes
Length of Pull: 13.87", Fixed
Barrel Length: 20", Smooth Bore
Choke: Cylinder Bore
Overall Length: 41"
Trigger Pull: 8 lbs. 1 oz. (as tested)
Weight: 7 lbs. 11 ozs. Unloaded
Magazine Capacity: 1¾"= 12, 2 ¾"= 8, 3"= 7
Accessories: Lock, Owner's Manual
MSRP: $930
OpSol Texas Mini-Clip 2.0 Flex $17



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