S&J Hardware

Mossberg 590 Series Magazine Extension

SKU MOSS-590
5 out of 5 stars 8 Reviews
$54.59 Tax
In stock
Capacity/ Extension Size *
Colour *
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Will fit Mossberg 590, 535, and 835 shotguns. Not compatible with the Mossberg Shockwave; it will fit, but won't allow for an extra round.

CNC machined from 4140 steel.

Finished product will be Cerakoted in the following colours:

  • Graphite Black
  • Flat Dark Earth
  • OD Green
  • Patriot Brown
  • Silver (Best match for electroless nickel)

Comes with:

  • 3 Position Sling Plate
  • C Clip (to install sling plate)
  • 1 Million Cycle Magazine Tube Spring
  • No Jam Follower - Type 3

Overall length:

  • +1 - 2.25 inches
  • +2 - 4.5 inches and is designed for pre-2017 590/590a1 or 835

Made in Canada.


Compatibility: *Likely not compatible with any clamp designed for use with a tube made of aluminum, or having a plastic sleeve covering. These tubes tend to be a little thicker in diameter.

License Required Non-Restricted
  • 5 out of 5 stars

    Great product

    Nice finish, works as described. Came with enough spring to do two mag tubes on my 590r. It holds 7+1 now and the tube is even with the barrel. Serrated nut fits securely with the factory detent pin
  • 5 out of 5 stars

    Excellent.

    Im in the UK, so our 590 can only have 24” or longer barrels. This +2 extension fits flush with the 24” barrel, a perfect fit, and so far has function flawlessly with the original spring. Also quick thank you to SJ for super fast delivery to the UK, mossberg bits are surprisingly hard/expensive to get hold of over here!
  • 5 out of 5 stars

    Fits Great!

    This fits good for my 590 Mossberg. Fun shooting an additional shell. Took me a bit to understand how long the new spring should be.
  • 5 out of 5 stars

    Excellent product

    Fit and finish is perfect! I used the one round extension on a mossberg 590 breacher and it cleared no problem.
  • 5 out of 5 stars

    Mossberg 590 mag tube mk II plus 1

    Excellent bit of kit. Arrived in UK within 10 days of placing order. Fits perfectly on my Mossberg Mariner and adds that extra 1 round capacity that is needed in IPSC competition. Major benefit is that it is a single piece, where other extensions comprise a nut and a tube and possibly an end cap as well (so three threads that might unscrew in use, where the S&J only has what amounts to a replacement factory end cap that includes a built in extension, so it stays put once attached. No barrel clamp needed). I would recommend it.
  • 5 out of 5 stars

    Mossberg 835 UltiMag

    Excellent product! Thankfully my Canadian brothers to the north have the part I needed. Thank you !
  • 5 out of 5 stars

    Mag Tube + 1 Extension - Mossberg 590

    Quick shipping, Excellent quality, Looks fantastic. Only tested with snap caps so far but everything seems to be working great and I love the HiViz follower. Very happy with this purchase and service from S & J Hardware. Will definitely be purchasing from them again.
  • 5 out of 5 stars

    Mossberg plus 1 extension

    No complaints. Quality feels excellent, installation was a breeze. Haven't had the gun to the range yet, and won't get the chance for a while, but feels nice and snug. Recommended.
Pairs well with

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