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Kwa H&k Usp Help

usp mag gas leak green gas problem new kwa hk efficiency

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#1 Corncake288

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Posted 09 February 2012 - 07:40 PM

Hey everyone, new KWA user here and so far I am EXTREMELY satisfied. Good job KWA! :clap: My USP, which I just bought from ASGI last week, is very nice but there are a few problems I have had so far with it. I cleaned the gun out of the box before I shot it according to one of the guides here on the forums (pinned topic) which includes cleaning and re-lubricating the five rail guides, the bucking (with VERY little oil) and the inside of the rails on the slide, ect. One of the most important problems is that the gas efficiency isn't as good as KWA/most people have said; well for me at least. I would probably get about one and a half mags out of one fill of green gas. I use Firepower/Palco Sports green gas that has an integrated fill nozzle unlike the screw on ones and I fill each mag for 15 seconds with three five second fills and I have tried two different green gas cans. The average temperature around here is about 65 degrees where I live and I also warm the mags in my pockets for about ten minutes so it is upwards of 75 degrees. I shoot one shot every three seconds and the gas still can't get more than a mag and a half full. Rapidly shooting (about 1 shot a second) yields only enough gas to fire off the last shot but not cycle the slide and lock back. Both the mag that came with the gun and the spare magazine (it has "Manufactured in Taiwan" on the spare one while the other one doesn't, that's how I tell) I bought are having this problem with gas efficiency. Another problem with the spare mag is that it leaks, very slowly, around the area where the gas is released from the mag (at the top by the valve?). I was told to store mags with a small amount of gas in them so I charge the mag with gas for three seconds and the next day, the spare mag had no more gas while the mag that came with the gun seems to have held the gas fine. I could hear a faint hissing sound when the mag is filled to full capacity with gas too. The second problem is that the safety would only engage if the hammer is either all the way back or half back (you can get this by either de-cocking the mag or pull the trigger in DA halfway). Any help with this problem is appreciated as I am a new KWA user with this being my first ever KWA as well as GBB. KWA was my only choice in GBBs for their unsurpassed customer service and build quality. Once again, I applaud KWA. :clap:

#2 Dirt Bag

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Posted 09 February 2012 - 08:32 PM

I have he HK USP ns2. I get about 1 1/2 nags per fill.  

The leak may just be the fill valve. You can gently unscrew it check and lube the inner fill valve o-ring. It is more likely the large rectangular o-ring that seals the bottom plate to the mag body.

At 4:30 of this video he takes apart the mag. I can't recommend the Teflon tape.  It seems excessive to me. I mainly posted this vid to help you get the mag open.



To fix the seal I used echo1 air seal lube which worked great. I think it is basically rc shock oil. It is similar to the oil that came with your gun but thicker.  The oil that came with your gun will probably work too.  Some others have soaked their o-ring overnight in silicon oil.

Hope this helps. BTW my USP is great. It is very accurate. You will enjoy using it.

Edited by Dirt Bag, 09 February 2012 - 08:34 PM.


#3 niko_gpsy

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Posted 10 February 2012 - 07:02 AM

Hey Corncake,

Welcome to the KWA forums.
It has been my experience that it is not really out of the norm to get a mag and a half of bb's out of 1 fill.  I know that many members here have reported even up to over 2 mags with just one fill but there are variables here you would have to consider.  In summer time where the temperature is near 90F I can get a little over 2 mags worth of shots with one fill but at the temperatures you have posted it seems normal to me.
And if you hear hissing from the release valve, I recommend placing a drop of silicone oil that came with the gun on the valve and work it in.  Do this when the mag is completely empty of gas. The o-rings may be a bit dry for a good seal and this should solve your issue.  And you can even try tightening the valve a bit as well but to do this I would recommend a valve key so that you don't damage the valve during the process.
I hope this helps.

#4 Corncake288

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Posted 10 February 2012 - 06:16 PM

Thanks guys, the leaky mag was fixed and I will assume the gas consumption is fine because the temperature isn't at the optimal range for GBBs. I just noticed another problem though. With the hop up off, the BBs only fly about 30 feet before dropping to the ground. Is this normal? I don't really like to use the hop up as it varies between distances and I run around a lot. This really isn't a problem but I am sort of a perfectionist (which is why I bought a KWA) and the spring on the spring guide seems to be bent and deformed so when you rack the slide, it sounds very.. ugly, if that is correct. Is it supposed to be like this or did I just get a bad spring?

#5 gcw360

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Posted 10 February 2012 - 06:19 PM

Why not post a picture of the spring guide?  It's the best way for us to determine if there is an issue.

#6 Corncake288

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Posted 10 February 2012 - 10:16 PM

Here is a picture. See how it is slightly bent outwards instead of being straight? I assume this is causing the screaking noise I am hearing. Is it supposed to be like this?

Edit: Oops, I forgot to actually attach the file. Apparently it is supposed to be like this so I am assuming it is fine. 500KB also seems awfully small for an attachment such as a picture.

Edited by Corncake288, 10 February 2012 - 10:21 PM.


#7 Dirt Bag

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Posted 10 February 2012 - 10:17 PM

How does it shoot with the hop up dialed in?  I believe you should get 60-75 feet of effective range.

My USP make the same sound. It only does it when I rack the slide. I don't notice it when I'm shooting. I think its normal.

#8 Corncake288

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Posted 12 February 2012 - 09:59 AM

Uh oh, the mag started to leak again. It leaks at the top of the mag by the area where the hammer strikes the valve button thing. I can't tell if it is the little rectangle in the middle of the top or the valve that is leaking. The slide also refuses to lock back when this mag is out of ammo but it works fine with other mags. I even found a mag half buried in the dirt at a game yesterday that works better than the brand new mag. Any suggestions on how to fix it? Also, which part is the serial number? The number on the silver plate on the frame, the number on the left side of the slide, or the number on the outer barrel?

#9 gcw360

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Posted 12 February 2012 - 10:45 AM

Is the mag leaking when filled or after you take a shot?  The valve may be loose or sticking.  I would apply a drop of silicone to the valve to see if that helps, be sure to work in the silicone.  If the valve is loose and leaking then you need to either send it in for repair or have someone tighten the valve assuming it is not faulty.

The number on the slide (left side) is the KWA serial number.

Can you post a pic of the mag that isn't working correctly? Focus on the front and the top left of the mag by the BB follower.  A damaged BB follower could be the cause of the slide not locking back.  A damaged valve could do that too however due to insufficient gas release.

#10 Corncake288

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Posted 12 February 2012 - 01:49 PM

I applied a drop of silicone oil to the valve and worked it in pretty well but it still leaks when I fill the mag. If I sent it in for repair, will KWA reimburse the shipping costs? Assuming it is still (do mags get covered with the 45 day warranty as well?) under warranty of course. Also, the slide not locking back problem seems to have went away so the only problem now is the leaky mag. Now that the temperature is warming up, the mags seem to get at least two mags full now, if not more.

Edited by Corncake288, 12 February 2012 - 01:50 PM.


#11 gcw360

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Posted 12 February 2012 - 02:34 PM

The mag is covered under the 45 day warranty.  You would need to pay for shipping out.  KWA will pay for return shipping.  If you can find a tech with a valve key then they can try to tighten the valve and that could solve the issue.

#12 Corncake288

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Posted 12 February 2012 - 04:39 PM

View Postgcw360, on 12 February 2012 - 02:34 PM, said:

If you can find a tech with a valve key then they can try to tighten the valve and that could solve the issue.

If you tighten the valve, would that void the warranty?

#13 gcw360

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Posted 12 February 2012 - 04:57 PM

View PostCorncake288, on 12 February 2012 - 04:39 PM, said:


If you tighten the valve, would that void the warranty?
Not unless you break it and so long as you use the correct tool which is a valve key NOT a screwdriver.

#14 niko_gpsy

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Posted 12 February 2012 - 05:00 PM

I have ruined a few release valves using a thin screw driver. :(

#15 Corncake288

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Posted 12 February 2012 - 10:06 PM

I guess my only option is to either drive down to Airsoft Extreme to see if they have a valve key or send it in... What is the estimated time to get the mag repaired/replaced if I do decide to send it in?

#16 niko_gpsy

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Posted 13 February 2012 - 05:50 AM

I would estimate 2-3 weeks.





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