KWA MP7 won't cycle completely

[FilthyHorse]

Hey guys, I've been using my KWA MP7 for a couple of years and haven't encountered this problem since recently, and I'm just stuck.

I load up a mag, pop it in, rack it, then the first shot goes off fine. From there it won't fire properly again without having me rack it. If I check the chamber I can see that no BB has been loaded in, however the hammer has been cocked, so I can pull the trigger and expel gas but that's it. On full auto, the first shot fires off then it's all dry firing.

Main suspect to me is something gas related, as if I was releasing more gas the bolt would go back further and the feed cycle would be completed. If I fire an empty magazine the bolt doesn't lock back, however I can rack it back to lock the bolt, further suggesting I'm not getting enough power to bring the bolt back.

Here's where it gets really weird. I have an NPAS valve installed and tried it in several positions, always with the same result, but when I changed it out for the original KWA valve and try and fire, all of the gas in the magazine dumps out of the barrel and chamber. I've lubed the mags and O-rings, and I've tried several magazines. This doesn't happen with the NPAS installed.

So I essentially have a bolt action MP7. What do you all think? Thanks for reading.

[Danke]

OK part one.

With gas guns most of the issues are with the mags. How many mags do you have and are they all KWA or are some KSC?

Now Part two.

If you put the stock bolt setup in and it runs fine then you know where the problem is.

Extra credit. What gas are you running and how hot is it outside?

[FilthyHorse]

Right! I have 5 mags, all KWA.

I don't have any bolt other than stock bolt, but I removed the modification to it that I had done previously and that didn't fix it.

Using Coleman propane, tried a new tank and a new adapter, bleeding the air from the mags when filling as usual.

Max 20 degrees C outside, tested in a 10 degree basement too.

Thanks for the reply!

[RainyEyes]

Have you looked at the rear of the gun where the rear pin holds the bolt? And what of the nozzle? Common points of failure on the kwa/TM mp7 is the plastic on the rear of the gun. If that moves out of place the gun might not cycle to reload a BB into the chamber.

[Freeze]

I used to have a KWA mp7. Sold it in anticipation of the new VFC AEG one.

I had a similar problem where it just wouldn't load the next bb. Turns out that the stock hop up bucking had swollen up due to oil getting into it. I replaced the hop up (which is a horrendously long process) and it solved that problem.

[hollywood...]

Tear it apart, clean and lube it.
I had the same problem with both of my MP7s

[Danke]

The swollen hop up rubber was a pretty typical thing when they first came out.

This is what I put in mine.

https://shop.ehobbyasia.com/falcon-e...ystem-7-1.html

[FilthyHorse]

Yeah the issue isn't that the BBs won't fire though, it's that they won't feed in because the bolt isn't coming back far enough to have the plastic part of the bolt spring back. I've had the swollen hop-up problem before as well, that's definitely not the case here.

I'm working on full mag cleaning at the moment, I'll see how that goes. Thanks guys!

[venture]

Carefully look over the nozzle for cracks.