A&K M249 Gearbox problem, Upgrade list?

Discussion in 'Gun Building, Modifications & Repairs' started by Casanova, Aug 7, 2012.

  1. Casanova

    Casanova New Member

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    Buffalo
    I have had my M249 for about 4 months now, and i have replaced the Barrel and Hop up assembly although i highly doubt that has anything to do with my problems, Recently during a game i was firing and it stopped mid burst (It was my 4th 10-15 round burst in the period of about a minute or so) And the gears started turning freely. Mind you the air nozzle is moving and spitting out a small puff of air, however it will not fire due to there being a lack of air pressure. The gears sound like they're moving freely almost as if my piston or gears are stripped. I'm inexperienced with repairing airsoft guns but i would like to learn and was wondering what you guys would assume the problem is before opening the gearbox. Would you guys suggest i go for it or should i take it to a shop? I will also purchase the parts myself to have them installed so what are the best gears/Piston to purchase for a mid/long range high ROF setup? Thanks so much,
    Will
     
  2. Casanova

    Casanova New Member

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    Buffalo
    Also, if i wanted to replace the stock A&K bearings, would skate bearings work? Namely the Bones Reds 8MM bearings? I'm pretty sure the bearings are the right diameter but would they stand up to use in a high rate of fire set up? thanks,
    Will
     

  3. Thunderbo15

    Thunderbo15 Active Member

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    Saint Charles
    It definitely sounds like stripped something if they are spinning freely like that, you might as well pop in it and check. The M249 gearbox is INCREDIBLY easy to get into due to the fact if has a quick change spring system installed.

    If your piston is stripped I would suggest you get an SHS 14/15 and glue the rack down and correct AOE as well as shim the gears. If your gears are stripped, and you aren't looking to change the ratio, look for some standard JG 18:1 gears.

    With the ROF, it depends what you consider a high ROF. Anything under 30 RPS is generally considered kind of medium to low RPS and isn't usually all that stressful on the gun unless you didn't tune them correctly or the part are crap/have defects.
     
  4. BoogerMc

    BoogerMc Airsoft Jedi Master Supporting Member

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    Akron
    I'm willing to bet you not only stripped your piston teeth, but you may have broken the open end of your piston off completely. Why do I say this because the exact same thing happened to one of our player's M249 and M-60 in the exact same game. Boy, talk about someone who was PO'd.

    As Thunder stated, the gearbox is easy to pull apart, there is a thread around here somewhere that has a link to a video that shows the basic strip down, I'd say search for M249 and you're likely to find it.
     
  5. SilentVectorX

    SilentVectorX Member

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    San Angelo
    The skate bearings will work if the inside diameter is 3mm, and they are 4mm wide. The question is if they are *really* better than the stock bearings or not. IMO it's not really worth upgrading bearings, just use bushings (which arent available for MG gearboxes yet). I upgraded to ceramics, and still managed to frag a bearing.
     
  6. Casanova

    Casanova New Member

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    Buffalo
    Thanks for the help guys, Gotta get a good work space set up and then open it up. Do you guys think there would be an interest in a build thread on it if i plan to overhaul the gearbox? i was thinking of replacing the piston head with the Element silent piston/ cylinder head set and i found an SHS piston with full steel teeth, It's a dark blue if that helps identify it. This M249 is going to be set up to help dislodge snipers so it's gotta have a decent bit of range. I say "Dislodge" simply because Marksmen are about as deadly as a golf ball in your throat. Haha :)
     
  7. Casanova

    Casanova New Member

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    Buffalo
    it was the piston! cracked 4 teeth straight off. haha thanks for the assistance AS!
     
  8. Thunderbo15

    Thunderbo15 Active Member

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    Saint Charles
    First things first, go check out clandestine Airsoft and shop around, he has stuff for super cheap, super cheap shipping, extremely fast shipping, and amazing customer service.

    I have heard pretty bad things about "silent" piston sets. The main thing being that they are not silent by any means and hardly reduce noise at all. That and they are not always reliable. Of course, it varies brand to brand, but I would avoid it. Just get a normal piston head (avoid metal if your going for a high ROF).

    Yeah a thread would be great if you want some help man!

    And if you want more range, look into doing a flat hop modification to your hop up. It might be a bit more of a PITA with an M249 hop up, but totally worth it. Hell, you would probably be getting way more range than all the kids there with stock sniper rifles lol
     
  9. Casanova

    Casanova New Member

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    Buffalo
    Okay i'll be sure to check out clandestine :)
     
  10. SilentVectorX

    SilentVectorX Member

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    San Angelo
    You're going to need a rigid concave piece of material for the hopup to push down on (i.e. a HunterSeeker Armory "Snibble"). I think he also sells a M249/M60 Hopup Unit designed for R-Hops that may be more compatible with a simple Flat Hop.
     
  11. Casanova

    Casanova New Member

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    Buffalo
    Hmm there's some info i didn't wanna hear. haha I've been skulking around the forums and I've noticed R hop and IR hop come up quite a bit and i looked at the guide for them, they must be a relatively recent update in the airsoft community because when i was most active before back in 2010 I'd never even heard of such a thing. I assume the premise behind it is the fact that instead of a rubber sheet pressing down on the projectile in the center, it has a thick rubber sheeting over the hop window to spread the pressure evenly, Correct?
     
  12. SilentVectorX

    SilentVectorX Member

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    San Angelo
    Basically yes. THe R-Hop cradles the BB as it applies spin, rather than a standard bucking/nubbing which is like hitting a speed bump.

    Half of my AEGs (all my primaries) are R-hopped or ER-hopped. There are many people that can install them for you.
     
  13. Casanova

    Casanova New Member

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    Buffalo
    I feel like I'd be able to install it myself but clandestine's outta stock of the R hop. IS the ER hop Comparable? :confused:
     
  14. Thunderbo15

    Thunderbo15 Active Member

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    Saint Charles
    The ER hop is an elongated, improved version. However, it will require you to cut your barrel to use it.

    If they aren't on clandestine just contact hunterseeker5 himself and order them. They are very similar prices, his is actually probably a bit cheaper