Unlock the full potential of your Mossberg 590A1 with our robust magazine extension.
This accessory boosts your shotgun’s capacity, allowing for more rounds between reloads. Crafted for durability and a perfect fit, it ensures consistent performance in every situation. Elevate your shooting experience with this essential upgrade.
+1 - 2.25 inches
+2 - 4.5 inches and is designed for pre-2017 590/590a1 or 835
Fits Mossberg:
Comes with our:
CNC Milled from a solid block of 4140 steel.
Finish: Cerakote Graphite Black.
100% Made in Canada.
Every multi-piece magazine extension has at least three components: a cap, a tube body, and a nut. Each junction is a potential failure point - a gap where a shell rim can catch, a seam where the bore stops being perfectly round, a thread junction that loosens under recoil.
Conventional tubes are made from extruded or DOM tubing. That means a weld seam running the length of the bore. When we machine from solid barstock, the bore is perfectly round from end to end because it was cut that way, not formed and welded.
There is no cap to unscrew. No nut to back off. No seam for a shell to catch on. One piece. One continuous bore from the threads into a lead end - the same approach used in barrel manufacturing.
Magazine tubes live under the gun, at the front of the gun, where they hit things. Door frames. Truck beds. Barricades. Obstacle courses. A thin-wall aluminum or extruded steel tube that dents on contact is a reliability problem waiting to happen - a dent in the bore is a jam you can't clear in the field.
4140 is the same chromoly steel used in most shotgun barrels. We machine from custom-sized barstock using specialized CNC tooling developed over eight to nine months of R&D just to get the process repeatable.
The weight difference between our machined steel and a machined aluminum equivalent is measured in ounces, not pounds. Nobody takes aluminum suppressors into the field. This is the same principle.
Factory magazine tubes have notoriously inconsistent threading. Remington uses different thread pitches across generations. Mossberg, Winchester, Benelli, and Beretta all have their own specs, and the quality control on factory tubes - even from the big three - varies widely.
We developed a proprietary hybrid thread design engineered to account for the manufacturing variation across generations and models of the major shotgun brands. The result: a tube that threads on cleanly without being so loose that it compromises the bore.
Every tube is laser-engraved with the exact model and length - Mossberg 590 +2, Remington 870 +1 - so there is zero ambiguity about what goes on what gun.
Every SJ Hardware magazine extension is Cerakote finished. Not phosphate. Not black oxide.
Phosphate was a World War I solution for giving bare steel the ability to absorb oil so it doesn't rust. It works. It is also what you use when cost is the primary driver.
Cerakote is harder, more corrosion-resistant, and looks like it belongs on a firearm that costs what yours cost. Standard finish is black. Factory-matched Cerakote colors are available for popular models - including the Benelli M4, Beretta 1301, and Stoeger M3K - at no additional charge.
Extension fit my 590 perfectly, the OD color matched the factory shotgun color perfectly as well. Trimmed the supplied spring to the same length as the factory spring to get a total of 7 shells in the magazine tube and so far no troubles, everything cycles fine. Looks great and functions great, highly recommended!
Well made sturdy and securely attaches. I saw a video about the interaction with the detent. The model shown had holes, mine has V notches cut. I have shot about 40 buckshot the first time out and had no issues with it coming loose. I left 5” of spring out of the magazine tube and that seemed perfect, no feeding issues at all. I do recommend this product.
This fit my model Mossberg model 50765 590A1 perfectly and went on easily. The quality, workmanship, and finish are flawless. After removing the mag tube nut, be careful when removing the factory spring stop, which is very tightly installed. I used a flat screwdriver, protecting the fine threads on the thin tube by keeping a thumb just past the end of it so the screwdriver couldn't hit the tube. There was no need to remove the mag tube to install the SJ follower. Instead, once the spring is out, push the follower forward as far as you can, then feed a bit of the old spring in through the receiver and push the follower a few inches, then remove the spring, and then point the shotgun's muzzle at the floor and shake it, up and down, and it should just slide right out.
Extension fit my 590 perfectly, the OD color matched the factory shotgun color perfectly as well. Trimmed the supplied spring to the same length as the factory spring to get a total of 7 shells in the magazine tube and so far no troubles, everything cycles fine. Looks great and functions great, highly recommended!
Well made sturdy and securely attaches. I saw a video about the interaction with the detent. The model shown had holes, mine has V notches cut. I have shot about 40 buckshot the first time out and had no issues with it coming loose. I left 5” of spring out of the magazine tube and that seemed perfect, no feeding issues at all. I do recommend this product.
This fit my model Mossberg model 50765 590A1 perfectly and went on easily. The quality, workmanship, and finish are flawless. After removing the mag tube nut, be careful when removing the factory spring stop, which is very tightly installed. I used a flat screwdriver, protecting the fine threads on the thin tube by keeping a thumb just past the end of it so the screwdriver couldn't hit the tube. There was no need to remove the mag tube to install the SJ follower. Instead, once the spring is out, push the follower forward as far as you can, then feed a bit of the old spring in through the receiver and push the follower a few inches, then remove the spring, and then point the shotgun's muzzle at the floor and shake it, up and down, and it should just slide right out.
