Leaky Mag Fix

Okay, it’s bound to happen at some point, that GBB mag is going to leak. Maybe it will be a trickle, maybe it’ll be like a the exhaust of a F22 Raptor… but you know it might just happen. So what are you going to do about it????

1) Find the leak

The first thing we need to do is find out where the leak is coming from. Is it the bottom plate? Is it the fill valve? Is it the hammer valve? Of course you could always just listen to the mag for where the hissing sound is emanating from, but it might not be that strong of a leak. So now what? Strip the mag down to the essentials. By this I mean, remove the drop plate (the thing that covers the bottom plate where the fill valve is located, then remove the spring that pushes up the bb’s and the follower. Now put a bit of gas in the mag and submerge it vertically in water completely. You might need to wipe of any bubbles that formed against the mag as you submerged it. Then watch for leaking. If you see bubbles coming from the hammer valve, then you know that’s a point of leakage. Now turn the mag over. If you see bubbles forming at the fill valve or the bottom plate, then you’ll have a leak.

2) Fixing the Mag

We’re going to look at the most common leak, the bottom plate. The usual culprit is the o-ring (which is actually a square most of the time in these mags), that forms the seal between the bottom plate and the mag walls. There are a lot of schools of thought on how to fix this. Some say to wrap it with Teflon tape, others say to soak the o-ring in silicon lube, other say soak it in brake fluid. Personally I’ve tried some of these ideas, and for the most part they are temporary. I’ve never had the silicone lube make a difference, and the brake fluid can deteriorate the rubber, and the Teflon is a pain to get right and will leak again at some point anyway. I have found that applying some RTV Silicone Gasket Sealant works like a champ. There is a trick to it though. Leave the o-ring in place on the bottom plate. Then put a very thin layer of RTV all around it. Again, make sure the layer is thin. Too much and it’ll ooze out everywhere when you put the mag together and could accidentally gunk up your fill nozzle. Now put your mag back together. Wait 24 hours!!!!! I cannot stress this enough. The RTV needs to set up to be strong enough to handle the pressure of the mag. After 24 hours put a little bit of gas in it. Listen for leaks, if you want dunk it back in the water and watch it. If there are no bubbles you’re good to go. I would suggest making sure your mag is 100% dry before fully reassembling it and firing. This of course can be sped up with the use of your wife’s / sister’s / girlfriend’s / personal hairdryer.

Sorry for the lack of pictures as I totally forgot to take pictures of the mag when I was repairing it. If I end of fixing someone else’s or a new mag I come across, I’ll make sure to take pics and post them here.


tags: airsoft technical fix leaking leaky mag magazine

3 responses

22 05 2014
wewex007

How about the fill valve? It leaks from the fill valve…

22 05 2014
Infected Armory

If it’s leaking from the fill valve you need to figure out where. It could be leaking from one of the inner o-rings or from the o-ring that seals the valve to the body of the mag. Usually I just replace the valve at that point though. If you’re having a hard time getting it sealed, you can always send it to our service center for repair. Check out http://infectedarmory.com for more info on repairing your gun.

5 04 2015
Jeff Gross

Thank you for posting this fix, I had a KWA mag with the square o-ring and retention pins holding it in but they didn’t hold it tight enough. This fix worked perfect and $4 to fix as many mags as I need is well better then 1x square $10 o-ring that might not even be the solution.

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