Description
The Mossberg 590A1 Retrograde is what happens when a company stops trying to modernize a design that the military already signed off on. Item 51665 puts the mil-spec 590A1 action into walnut furniture, adds a heat shield over a 20 inch heavy-walled barrel, and leaves everything else exactly as the armed forces specified it.
That means a metal trigger guard and a metal safety instead of polymer, a heavy-walled barrel that will take abuse a field gun would not, dual extractors, twin action bars, positive steel-to-steel lockup and an anti-jam elevator. The Mossberg 590A1 Retrograde holds eight in the tube plus one in the chamber, weighs 7.25 pounds and measures 41 inches.
The walnut is the part people notice first and the part that makes this gun worth its price over a synthetic 590A1. It is checkered, it is real wood, and against the parkerized steel it looks like something out of 1968 rather than something out of a catalog.
Features of the Mossberg 590A1 Retrograde
- 20 inch heavy-walled barrel with a factory-fitted ventilated heat shield
- 8+1 capacity, chambered for 2.75 and 3 inch shells
- Ghost ring sights, protected and adjustable
- Walnut stock and forend with checkering, and a vented recoil pad
- Parkerized finish throughout, as issued
- Metal trigger guard and metal safety rather than polymer
- Top-mounted ambidextrous tang safety
- Drilled and tapped receiver for an optic base
- Clean-out magazine tube with a removable end cap
- Dual extractors, twin action bars, positive steel-to-steel lockup and an anti-jam elevator
- 41 inches overall, 13.87 inch fixed length of pull, 7.25 pounds
What mil spec pump shotgun construction actually buys
- The heavy-walled barrel is thicker than a standard 590 barrel, which is the single biggest difference and the reason the A1 passed military testing
- A metal trigger guard and safety will not crack when the gun is dropped on concrete or crushed in a rack
- A mil spec pump shotgun is built to a specification rather than a price, and the parts are held to tighter tolerances as a result
- The clean-out magazine tube unscrews so the spring and follower can be serviced without a gunsmith, which matters on a gun that lives loaded
- Twin action bars and an anti-jam elevator are what keep it running when technique gets sloppy under stress
Mossberg 51665 specifications
- Item number: 51665
- Gauge: 12
- Chamber: 3 inches, also handles 2.75 inch shells
- Capacity: 8+1
- Barrel: 20 inches, heavy-walled, with a ventilated heat shield
- Choke: fixed cylinder bore
- Sights: ghost ring
- Stock: walnut, checkered, with a vented recoil pad
- Finish: parkerized
- Safety: top-mounted ambidextrous
- Receiver: drilled and tapped
- Overall length: 41 inches
- Length of pull: 13.87 inches, fixed
- Weight: 7.25 pounds
- UPC: 015813516655
Ghost ring sights and why they belong on a fighting shotgun
Ghost ring sights are the right answer on a shotgun and the wrong answer almost everywhere else. The rear aperture is deliberately large and thin-walled, so your eye ignores it and centers the front post automatically; under pressure you look at the target, the ring blurs out, and the post lands where you are looking. A bead gives you speed with no precision and a rifle notch gives you precision with no speed. Ghost ring sights shotgun setups give you both, and they let you shoot slugs to a hundred yards with real confidence.
Both sights are protected by steel ears on this gun, and the rear is adjustable for windage and elevation. The receiver is also drilled and tapped, so a red dot is a bolt-on job if you prefer one, without losing the irons underneath.
The heavy walled heat shield barrel
The heavy walled heat shield barrel is the defining feature of the A1 and the reason it costs more than a standard 590. The barrel wall is thicker than the civilian gun, which adds weight forward, damps recoil, and survives the sustained firing schedules the military test protocol demands. The heat shield over the top is not decorative either: fire a box of buckshot quickly through any shotgun and the barrel becomes genuinely too hot to grab.
It is fixed cylinder bore, so no choke tube of any kind fits it. That is correct for the job. Cylinder bore opens a buckshot pattern quickly at the distances this gun is for, and it shoots slugs without complaint.
Ammunition for the Mossberg 590A1 Retrograde
For a 7.25 pound gun, full-power buckshot is manageable but not pleasant in volume. Rio Royal Buck Low Recoil 00 buckshot is the sensible place to start and gives up very little at defensive range. For full-power work, Barnes Defense 12 gauge 00 Buck patterns well out of a cylinder bore. Pattern whatever you choose on paper at seven, ten and fifteen yards before you trust it.
How it compares to the rest of the 590 range
The 590A1 9-Shot in synthetic is the same mil-spec gun with a polymer stock and one more round, and the 590A1 Magpul Series adds Magpul furniture with an adjustable length of pull. If you want the Retrograde look on the lighter standard action, the Mossberg 590 Retrograde is the 18.5 inch gun without the heavy barrel. Mossberg publishes the full specification on the official 590A1 Retrograde page.
Why this firearm earns its place
- Genuine mil-spec construction with a heavy-walled barrel, metal trigger guard and metal safety
- Walnut furniture on a fighting shotgun, which almost nobody else offers at any price
- Ghost ring sights fitted and protected from the factory, plus a drilled and tapped receiver for an optic
- 8+1 on board, which is two more than most defensive pumps hold
- Clean-out magazine tube, so a gun that sits loaded for years can actually be serviced
This suits the buyer who wants the 590A1 the military buys but would rather look at wood than plastic, the collector who appreciates the original configuration, and anyone who wants one shotgun that will outlive them. At 7.25 pounds and 41 inches it is a substantial gun, which is the honest cost of the heavy barrel.
Every firearm we ship goes to a licensed dealer in your state for the transfer and the background check. Call us if you need help finding a shop near you that accepts transfers.
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