Remington 870 Ejection Window Modification

I’ve heard about this Remington 870 modification several times. I was not sure about it because it requires modification of the ejection window and it cannot be undone. This is the most radical way to improve reliability of your Remington 870, so if you don’t have many issues with extraction you don’t need it.

WARNING! This modification cannot be undone. Make it only if you are 100% sure.

But as author of the Rem870.com blog I need to check everything about Remington 870 and see if it works.
This upgrade will not harm your shotgun. It functions properly, but only tests and several hundreds of rounds can tell if this upgrade is good.

Here you can see two Remington 870 receivers, one is standard, secone one is modified:

Remington 870 Ejection Window Modification
Remington 870 Ejection Window Modification

Start process with fixing Remington 870 receiver in vise:

Remington 870 Receiver Fixed in Vise
Remington 870 Receiver Fixed in Vise

Then, carefully measure how much metal you need to remove with Dremel to make front part of the ejection port rectangular:

Carefully Measure How Much of the Metal You Need to Remove with Dremel
Carefully Measure How Much of the Metal You Need to Remove with Dremel

Remington 870 Ejection Window Modification

Vitaly Pedchenko

My name is Vitaly Pedchenko, I started this blog and forum to share information, tips, photos, and advice about the Remington 870 shotgun, accessories, and upgrades. Now I also own AR-15 rifle and MP5 pistol caliber carbine. I am firearms instructor, competitive shooter and IPSC Range Officer. I participate in practical shooting and 3-Gun competitions because they are the best way for me to test equipment and upgrades under stress. I am member of the PRACTICA shooting club. I also participate in REAGO, which provides Tactical Combat Casualty Care training. The main purpose of the Rem870.com blog and forum is to have a compilation of information about the Remington 870 shotgun in one organized, accessible place.

12 thoughts on “Remington 870 Ejection Window Modification

  • 14.01.2013 at 12:59
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    Outch !!!! Can’t to that to my gun !!!! I prefer it as it is ……. even with a few shortcomings …. even though I have not noticed anything of that sort !!!!!

    Besides, can’t understand what type of problem this modification would correct .. !!!!

    Reply
    • 14.01.2013 at 13:51
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      Theodore, I was very worried about my gun too! But I did this for educational purposes.

      Some say that rectangular form of the ejection window ensures more reliable extraction of fired shells.

      Reply
  • 14.01.2013 at 16:54
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    Pretty extreme approach, but it seems like it might be most applicable on the 870 SuperMags. The 870 receiver was never designed to cycle those 3.5″ shells, and I’ve heard that the SuperMags won’t always eject them reliably.

    Reply
    • 14.01.2013 at 19:34
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      The theory that I’ve heard is following: rounded edges doesn’t allow shell to be extracted as fast as possible, that is why Remington 887 and Mossberg shotguns have rectangular ejection windows.
      Not sure if it’s true but I did this mod to see how it’s going to work.

      Reply
  • 14.01.2013 at 23:51
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    Ага, молодца.
    На самом деле есть один нюанс: подобную опиловку надо делать с осторожностью.
    Если передняя часть окна будет строго прямоугольной формы, гильзы будут выбрасываться не так энергично, вяленько.
    “Печная труба”, от которой данный вид напиллинга помогает избавиться, случается, в основном:
    1. на патронах с излишне закруглённой закраиной;
    2. на морозе, когда жёсткость пластиковой гильзы значительно возрастает.
    На приличных патронах при плюсовой температуре невыброс гильзы достаточно редок.

    Reply
    • 08.02.2013 at 20:59
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      will this harm the shot gun. we had this model in the black sea in constanta, romania’.i am an albanian- italino, nat’l’.i served, in the american service.

      Reply
      • 09.02.2013 at 04:41
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        No, it will not harm the shotgun. But this procedure is very radical and not required for most of the shotguns. I needed to test this modification to see if it works.
        So, if your shotgun works properly, don’t do this.

        Reply
      • 09.02.2013 at 12:07
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        У меня с этим улучшение оружие наработало уже несколько тысяч выстрелов – и наработает ещё столько же.

        Reply
  • 08.04.2013 at 19:56
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    The part that you took out that came with the gun (later replaced ) was in back wards. That part when installed the opposite way can come out easy using a big rounded head nail with pliers. Hole the end of the nail. Insert head of nail thru the hole and pull part out . easy I have done it that way for yrs. Ohh The part comes out in seconds about two LOL

    Reply
  • 14.02.2017 at 07:13
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    i have to do this to cure stovepipes
    so after 4 years what do you think about that mod you made ?

    Reply
    • 15.02.2017 at 04:44
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      I don’t think it was necessary. Choose good ammo, polish chamber and get good extractor, that should fix all of the problems.

      Reply
      • 15.02.2017 at 15:39
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        i polish the chamber already
        also i have a bore brush and give it some passes every time i clean it
        yesterday i put the volquartsen extractor
        and i filed a litle the port
        then i shoot about 20 rounds hunting with no problems
        but as you say it only happens with specific ammo
        just a different brand /type of ammo not always more expensive
        may work better

        Reply

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