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Magpul forearm on 590m

Discussion in 'The Workbench: Builds And Modifications' started by Kenneth07ex, Jul 1, 2020.

  1. Kenneth07ex

    Kenneth07ex .22LR

    Messages:
    10
    Hey everyone, I'm trying to fit a magpul forearm on my 590m. And fitment charts don't really include the 590m for aftermarket parts of most any sort. This forearm is made to fit the 590a1. And claimed to fit all 590 models. I probably should've done a bit of measuring first. But instead took the internet's word that it'd fit, with only a bit of relief cut in for the heat shield. I was ready for that slight modification, but substantial modification won't work for me.

    It's actually about an inch too long for the slide tube mount. I remember seeing somewhere, that there's two different size tubes for the different models. And IIRC, there's about an inch difference between the two.

    Here's the question, do I look for a longer action tube? Possibly there's a longer nut that'll reach down in there? Or look for a shorter version of the magpul grip? I'm thinking that replacing the magpul grip with the shorter version would be easier, and probably best. Since it would continue to use the specs as designed. And would likely only be a swap return. Or if the longer nut is a possibility, that'd work too. But I have no idea what other models have the shorter tube. Since I'll have to know what to ask for from magpul. So what model comes with the shorter tube? And is the tube the same circumference?
    Last edited: Jul 1, 2020
  2. Smashing Pumpkins

    Smashing Pumpkins .410

    Messages:
    38
    There is a whole thread on forend tubes that is a sticky in the 500 forum:
    http://www.mossbergowners.com/forum/index.php?threads/what-size-forend-tube-do-i-need.13033/

    Your simplest solution is probably to get the Hogue adapter kit, which is just a longer nut.

    if you want to do it right and are not in a hurry, I have a 590 on order that comes with the longer forend tube, and I need the shorter one. I could swap you. But with the current shortage, it may be a long time until I get delivery.
  3. Kenneth07ex

    Kenneth07ex .22LR

    Messages:
    10
    Thanks for the reply. I looked at the sticky, and that's what made me think about a longer nut. The information is either very simple, or I'm overthinking it. So I'll probably try the longer nut, and see if that does the trick.

    I really like the 590m, because of the ability to immediately load, or unload. Which I feel I need because of grandkids, and a home defense weapon. Other than that I'd probably gone with the 590a1. The lack of aftermarket support, or fitment information is just icing on the cake. Since there's a lot of stuff on this gun, that's just a tiny bit off from the more popular a1.

    Before I settled on this model. I placed a notify me by email when available tag on buds website, for several models. That was almost three months ago. Still haven't heard anything. So you're probably right about the wait. I ended up going with gunbroker. Saved a few bucks too.
  4. Smashing Pumpkins

    Smashing Pumpkins .410

    Messages:
    38
    Wow! Well done. Wish I could do that. The model I ordered is going on Gunbroker for about twice the price I was able to order it for locally. That is, when you can find it on Gunbroker.
  5. Kenneth07ex

    Kenneth07ex .22LR

    Messages:
    10
    That doesn't surprise me. My buddy bought a 590a1 for about three fifty last year, NIB from buds. That's what inspired my purchase. When I priced it, six months later, they were running five twenty nine IIRC. And they were out of stock.

    Unsurprisingly though, my LGS had a couple of the 590m in stock. Don't know about the other models, since I didn't look for those. But the price was around six hundred last time I was in there. I certainly hope mossberg can get more of the 590 models out on the market soon. Covid-19 lockdown has been tough on inventory everywhere. Good luck in your search.
  6. Smashing Pumpkins

    Smashing Pumpkins .410

    Messages:
    38
    Thanks. Supply shortages around here are off the hook. I doubt if there is a new pump action shotgun in stock in a any gun store within 100 miles of me. I ordered what I wanted at the pre-Covid price. Mossberg hasn't built it yet, but they will. May take months, but I have others to shoot in the meantime. No way I am paying current Gunbroker prices.
  7. OR3GUN

    OR3GUN Sponsor Sponsor

    Messages:
    220
    590m-LL.jpg
    We had no problems installing the Magpul forearm on our 590m that DIDN'T have the heat shield. The included Magpul insert for the 590A1 should work with your 590m unless Mossberg changed something since we acquired the two we have in-house. The heat shield interference may be another story.

    William

    http://www.OR3GUN.com
  8. Kenneth07ex

    Kenneth07ex .22LR

    Messages:
    10
    The slide tube is most definitely too short. I can see that it's close to an inch shy of where it needs to be, to catch the threads. I've ordered the adapter nut, and when it's locked down I'll try to reinstall the barrel. Then if it hits the heat shield as expected, I'm fully prepared to modify the foregrip a bit.
  9. OR3GUN

    OR3GUN Sponsor Sponsor

    Messages:
    220
    It required some effort to get it to fully seat over the action slide. Maybe some more pictures will help you verify that you've got everything seated.


    590m-Gray-Side.jpg

    590m-Gray-Tape.jpg

    Again, we don't have the heat shield version to check, but the above should help with measurements.

    William

    http://www.OR3GUN.com
    Kenneth07ex likes this.
  10. Kenneth07ex

    Kenneth07ex .22LR

    Messages:
    10
    Finally got the adapter nut in the mail. So I was able to finish this thing up. Took quite a bit of modification to the foregrip, to accept the nut. Then I had to further modify the foregrip to clear the heat shield. Lastly I had to modify the heat shield stabilizer on the front bottom of the heat shield.

    Not much to it, except for the endless disassembling, and reassembly. All to make sure not to remove too much material. I think it turned out pretty well. 20200806_133453.jpg
    Pawpaw likes this.

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