Frequent Jamming, KWA GBB
 

Gun is a KWA LM4 PTS Magpul edition

When I first got the gun, it fired all 38 BB's consistantly and without a problem.

Now it seems to jam about 1-3 times per mag, when i pull the bolt back there are 2 BB's in the hole, one actually in the hole whereas the other is on the side a bit..

So no idea whats going on here, is it loading 2 BB's during 1 cycle? w/e it is, its pretty annoying. I lube the internals up regularly.

It is cold here and I fire outside, but the gun is warm when I fire, and after about 5-10 rounds it jams.

I'm forced the pull the bolt back, remove the mag, shake it for that added BB to fall out, than put the mag and go at it again.

I feel I actually bought a Real M4, damn thing keeps jamming

When is the last time you lubed the inside of the bolt where the nozzle sits? I've found dry GBBR's can jam, chop bbs, and double feed.

You're absolutely right, forgot all about Lubing that part. Now that it is lubed she fires consistantly through the whole 38 rounds

Funny thing happened

My trigger would get stuck, I'd fire, trigger would get somewhat stuck backwards, i'd have to move the selector switch to safety and back for it to go forward..

Turns out that double feed problem i had sent a few BB's into the trigger assembly, there was about 3-4 of them in there all broken up, lol.

I cleared them out and shes working again.

Fricken thing

I hope this isn't a common issue. BTW, how's the hop up unit in the LM4? Is it consistent?

I'm glad to read this thread knowing that I'm not the only one with a problematic KSC/KWA M4 GBBR. My GBBR is the KSC version M4A1. It gets random double feed every once in awhile (every 5 mags or so). 2 BBs jumble up as they are trying to enter the barrel at the same time and the nozzle would pinch one of the bbs against the ramp causing the nozzle to deform.

This is a very frustrating problem, and yes it does feel like owning a real M4A1. But this jam is not fixable with "tap-rack-bang" or simple "strip-and-rackrackrack".The bbs would stuck and need a tool to pry them off.

I notice that this double feed tend to happen when the pressure in the mag is low or during rapid firing.

I cannot fathom why 2 bbs can get out of the GBBR mag at the same time. I tried pinching the lips of the mag with a pliers to make a tighter opening; it helps a bit but not completely solving the problem. I tried with other m4 mags (including the ksc pmag), still jams.

I lubed the exterior where the nozzle sits in the bolt regularly with regular silicone oil and it's still double feeding. I will try using a thicker silicone to lube the outer part of the plastic nozzle and see if it helps.

If you are still experiencing double feed after you lubed the nozzle, please write it here so we know what works and what doesn't.

I'm going to do a complete breakdown tonight and see what's the culprit.

Thank you

They are not feeding 2 BBs at once. One feeds and that BB does not leave the chamber; the bolt cycles and feeds a second BB (and in some cases a third and so on).

If the hopup rubber is saturated with oil it will swell up. Then the BBs will jam up.

Folks have a whole elaborate procedure to soak the rubber in chemicals to flush out the oil and dry it. It's easier to just swap it out.

It's a learning curve on how much oil to run in your mags. I have been told that KWA USA won't warranty GBB's run on propane because of users dumping BP levels of oil into them and then returning them for refunds because they've ceased to function.

In my case, the 2 bbs don't even enter the chamber. They just stuck around the ramp. I'm flabbergasted on how 2 bbs can leave the mag at the same time.. It isn't the mag because the same thing happens when i tried other mags as well. I think it's either the nozzle or the bolt's fault.

Issue is gone - Just have to lube the Nozzle here and there, Lube around it, lube the part that extends out to push the bb from the mag into the chamber, etc. If you lube this every 4 mags or so she'll stop double feeding.

Mine would double feed and crush a BB, so it would jam, sometimes i'd have to use a rod to pop the BB's out of place.

But like I said lubrication (I use basic grease) fixes the issue!

Selling the bugger unfortunately because my car blew its gasket - expensive repair man.