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Thread: Surefire M80 Rails on M4 / M1014

  1. #1

    Default Surefire M80 Rails on M4 / M1014

    Wanted to post a problem that was brought to my attention by FIAVAIM and explains an intermittant FTE problem I have observed. After installing the M80 rail, I noticed that occassionally the bolt would not go all the way back after firing, causing a FTE. I kind of shugged it off but I have determined the cause.

    When you remove the barrel from the SG with the M80 installed, you will notice that if you apply some light pressure on the rear of the rail system it can cause the movable gas tubes to rub against the rubber that holds the rail system to the barrel. This seems to be caused by excessive play in that cut out in the rubber in the area of the tubes. The interference seems to make the gun unable to properly cycle.

    I attempted to reduce the play buy using a small bit of JB weld on the rubber, but JB weld did not seem to adhear. I found that 3M automotive tape was the perfect thickness and I happened to have a roll of 1/2" diameter that was perfect. This is doulbe sided tape, so I left the plastic strip on one side. I cut a peice of the double sided tape about 2" in length and it seemed to adhear well to the rubber. I put it on the 'bottom' part of the rubber, where it meets the bottom of the tubes. Not on the part where the tubes move, but the static tubes that are immovable on the barrel. This tape was the prefect thickness. It was not longer possible to apply pressure to the rail system and cause the tubes to rub anymore.

    I hope this will cure the problem but I will not be able to do a feild test until next weekend. Will post results here.

  2. #2
    Join Date
    Oct 2006
    Location
    Florien, Louisiana
    Posts
    249

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    Thanks for the info. I just got one and have not had a chance to go to the range. Keep us posted.
    Benelli M4 & SBEII
    Sig MPX, M400 & 716 DMR
    Sig 1911 Emperor Scorpion, P226 Tacops, P226 Legion, P320 Full & Compact, 1911-22, P238
    Ruger 10/22
    Remington 870 Tactical, 870, M700 in 300WM

  3. #3

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    Definitely keep us updated on this. I have the M80 on mine, have put about 100rds through it and have not had this problem/situation arise. With that being said, I don't think I am putting pressure on the back of the rail, my hand is about mid-length up the rail during firing.
    Doesn't the M80 have some notches on both side of the rail to mount to the Shotgun and keep the rail for moving.
    Thanks for the info

  4. #4

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    Quote Originally Posted by Lakotah View Post
    Doesn't the M80 have some notches on both side of the rail to mount to the Shotgun and keep the rail for moving.
    Thanks for the info
    Yes it does. But apparently if you put pressure (as I sometime do) in the right spot the rubber bearly hits the tubes and hinders their movement just enough to stop the bolt from going all the way back. Does nto do it every time of course. I do think it has a lot to do with where and how you grab it and how hard.

    Simple fix, I will have to post some picts if it fixes it.

  5. #5

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    Ya, pics would be good and a lot of help for anybody running into this problem in the future.

  6. #6

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    I've shot over 1,000 rounds though mine and finally decided to clean it. I noticed the rubber on the inside was somewhat melted and stuck on the mag tube and the tubes the pistons sit inside. It took me a while to scrape it off, but the M80 rail doesn't seem to be damaged at all. Ive never had any failures from the rail, other than all the little screws that hold the rubber to the rail popping out on me, it seems to be great.

  7. #7

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    hmm... might just have to try that

    seems like it helps prevent the pistons from sticking, ill have to see how cycles the rounds tomorrow.
    Last edited by fiavaim; 03-12-2008 at 11:12 PM.

  8. #8

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    I took my M1014 out to the range and put 100 rounds thru her without any malfunctions what so ever. I am very confident that this repair does work. Also, I noted that the tape did not stick to the tubes on the barrel even after all that firing.

    First of all, here is a picture of the 3M tape I used. It is available at WallyWorld and other auto parts stores. I have seen it in the store in 1/2" and one inch widths. 1/2" is perfect. This tape sticks great and is the perfect thickness. It is used to stick exterior body parts on cars, like bug shields, aftermarket ground effect kits, etc. It is pretty tough stuff.



    The red arrows point to the area of rubber on the M80 that the tubes can rub against causing a FTF:



    Note I held it up side down and the barrel is on the bottom.
    Last edited by Flame Red; 03-15-2008 at 04:23 PM.

  9. #9

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    Here is a pciture of it with the barrel removed so you can see where the tape is applied. The tape is the length of the fixed tubes that are welded on the barrel. Do NOT apply tape where the tubes come out and need to move! Leave the red protection on the tape as shown, the tape is sticky on both sides.



    and from another angle, this time I held it in the normal orientation.


  10. #10
    Join Date
    Oct 2006
    Location
    Florien, Louisiana
    Posts
    249

    Default

    Nice. Thanks for the pics. I will see how mine shoots and if I have problems I will give it a try.
    Benelli M4 & SBEII
    Sig MPX, M400 & 716 DMR
    Sig 1911 Emperor Scorpion, P226 Tacops, P226 Legion, P320 Full & Compact, 1911-22, P238
    Ruger 10/22
    Remington 870 Tactical, 870, M700 in 300WM

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