Problem Thread, Need Tech Advice.

Discussion in 'Gun Building, Modifications & Repairs' started by Darkrider9, Aug 11, 2012.

  1. Darkrider9

    Darkrider9 New Member

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    Alright, so I just got back from probably the worst airsoft game I've attended. I took a bad hit to my Adam's apple, and 3 hits directly to three of my knuckles at less than 10 feet, all of which have become blood blisters. On top of this, all my stuff broke. My custom DMR stopped firing, and it just makes an odd noise when I pull the trigger. Either the gears aren't meshing with the piston or there's a problem with the gears. My TM Five-seveN just won't shoot. When I pull the trigger the blowback barely goes back and a BB rolls out, it goes back a bit father each time, and after about 5 or so shots it kicks really hard and starts shooting normally. Sometimes it just doesn't do anything at all when I pull the trigger. Both mags were full of green gas and they aren't leaking. My launcher grenades also weren't working, but I'm getting some new ones.

    Does anyone have any insight on the pistol issue? I'll post more info later when I have time to take things apart and test them.

    Edit: I disassembled the pistol, and part of the barrel was getting caught on the slide itself. I cleaned and re lubed it, and it still sticks a little, but it will only stick if you pull the slide back lightly and set it in the correct place. On a regular cock it works normally. I ran 5 mags through it and it has yet to have a problem, so I think I fixed it. However I still don't know what caused it, I wasn't rolling it through dirt or dropping it or anything.
     
    Last edited: Aug 11, 2012
  2. Scarred

    Scarred Active Member

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    TM 5-7s have terrible valve problems. Mine does that too. It only happens on hot days though.
     

  3. Darkrider9

    Darkrider9 New Member

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    Ah you sniped my edit, that may be it, is there any way to fix this permanently?
     
  4. Scarred

    Scarred Active Member

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    Permanently? No. I called up Airsoft Extreme and there are only two ways to fix it. The first way is to do anything you can to keep your mags cold. A cooler works. But that way is kinda silly. They also said that you can try just a tiny charge of gas- like one second of holding a gas can to it. You see the reason why this happens is because gas expands in hot weather, and when the gas level in the mag is too high, the gun has trouble striking the valve. I am pretty sure that this only happens with TMs. I've heard that air expands less than gas so I am planning on buying a can of HF134a gas to see if this problem still occurs.
     
  5. Darkrider9

    Darkrider9 New Member

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    Okay thanks for the advice I'll keep my mags out of the sun.

    As for my DMR, I opened up the GB, and the piston rack was completely severed from the piston itself, so I need a new, preferably stronger one. It may have been that I didn't AOE correctly. It was an SHS 15 tooth.
     
  6. Shady

    Shady Administrator Staff Member Administrator Moderator Lifetime Supporter

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    I actually just talked to knief about this 2 days ago. You're experiencing what is called a light strike. Japanese pistols are designed for use with Duster gas. So if its hot and you're using propane, then your hammer won't have enough power to properly release the gas due to the increased pressure. The way you can fix it is to A) Put a spacer in near the hammer spring to increase the tension, creating a harder strike or B) use duster gas. I would personally go with option B.
     
  7. Lefse

    Lefse Well-Known Member Supporting Member

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    What about a Lonex piston? They are made of fiberglass reinforced nylon and have a heavily reinforced design. 2/3 of the teeth rack is steel, to increase durability, and the last third is the same material as the body, and are molded into the body. Good luck breaking any teeth on that piston, I've had a Lonex piston survive pre-engagement without taking damage. Only downsides is that they are pretty heavy because of all the reinforcement and the teeth are more narrow than an average piston, I recommend swiss-cheesing it.
     
  8. Darkrider9

    Darkrider9 New Member

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    I think the SHS one is made similar to that, but the entire rack is steel/metal. What happened was the rack was ripped out of the piston and the gears shredded down parts of the rack that were sticking out because it was pulled out of the piston itself, so I need a piston that has a strong bond between the rack and the piston itself, or as I said, this may be an AOE problem, I'm not sure.

    Heavy isn't a problem, because I usually only semi, but for this one game one person was picked to be the "heavy" and he got to auto at all times, and I was chosen, so I think I overdid it. However let it be known that I wasn't going auto for too long, really just a few second long bursts.
     
  9. deathmechanic

    deathmechanic Active Member

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    Did you glue your rack down? It could solve your issues.
     
  10. Darkrider9

    Darkrider9 New Member

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    No I didn't, I just put it in stock. I have to pick up another one, and I'll definitely glue it down. Could it have been the AOE though? I'd like to think my gun won't be breaking good pistons like this often.
     
  11. deathmechanic

    deathmechanic Active Member

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    AoE can be the cause. AoE if not taken care of is the death of many GBs. Gluing down your rack will help. Also there are no "good" pistons. You have to choose out of a bunch of piss poor made pistons, and hope for the best.
     
  12. Lefse

    Lefse Well-Known Member Supporting Member

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    The steel teeth rack fits very snugly in Lonex pistons, it takes a good bit of strength to take it out, so it should be able to take some punishment.
     
  13. Uller

    Uller Well-Known Member

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    The strongest piston I have ever used is the Deepfire titanium.It survived a Systema M170 spring on fullauto.That was 6yrs ago and im still ussing it in my Countersniper.
     
  14. Darkrider9

    Darkrider9 New Member

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    Alright so I'm definitely going to glue the rack down when I get it. The Deepfire Titanium Uller suggested sounds good, what effect would it have on my gun other than slower RoF?
     
  15. Lefse

    Lefse Well-Known Member Supporting Member

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    The piston won't really affect neither ROF or FPS. It may have negligible effect, but nothing noticeable really. I have actually killed 2 Deep Fire Tianium pistons, it did take massive PE with an M120 to do it though so they are pretty strong.
     
  16. alex

    alex New Member

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    full auto on a DMR build usually ends up with pre-engagement. since you didn't correct AOE, i'm going to assume your piston is heavy and using a high discharge battery.

    btw, DMR builds are locked on semi-auto. what rps and fps? metal piston head with piston bearing installed? pre-engagement usually rips the rack off pistons or caves it in. without knowing your gear ratio, motor and battery, i'm going to assume an improper DMR build.
     
  17. Darkrider9

    Darkrider9 New Member

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    Alright, thanks for the tip!

    It's my first build and it isn't finished, I still have a lot to do. I had hastily assembled the GB for this weekends game, and I didn't have time to pick up sorbo pads to help correct AoE. I didn't have a chance to test the rps or fps, but the rps seemed a lot higher than any guns I've owned, which is odd because all the parts I put in are for torque not speed. As you said pre-engagement probably was the problem, my fault for not taking the time to AoE correctly. The gear ratio is 18:1, Lonex Orange motor, and a 7.4v 1200mAh 20c LiPo.

    Edit: As for the semi auto thing, I haven't had a chance to remove FA yet, but my OCD is against having the auto switch be there but non functioning, so I plan to replace it with a 3rd burst. I don't know if it would still be considered a DMR then, if not, oh well.
     
    Last edited: Aug 12, 2012