M92FS Jamming - Rear assembly getting stuck forward

[SHÖCK]

I recentely bought a KJW M9 on ASC and it seemed to be working well at first but now it's developing a few problems. Every now and then it will not feed unless I manually rack the slide.

The biggest problem though, it that it often jams with the rear blowback assembly getting stuck forward. It just sticks there and even with force of hand, it's very hard to get it to back. You can see the return springs are bunched up and I am not exerting any force, it just sticks there and the entire gun will jam with the slide stuck with this piece trapped there in this position. The gun is being used on propane and I've never seen this issue until today after a couple of weeks of ownership. I don't think this piece is ever supposed to be forward like this, it's supposed to be an open chamber design. When it gets stuck, it's very hard to get it unstuck and to go back again.

What's going on?

[KND]

You may want to take out the complete blow back unit out and check the spring for the nozzle, the spring might be stuck or the worst parts is getting bend, you may replace the spring or try to fix them. Hope it help.

[SHÖCK]

It appears the plastic one-piece nozzle assembly (the is no spring inside the nozzle like on diagrams, it just doesn't exist for some reason) is getting caught on the rubber edges of the rear blowback piston head attached to the back of the gun. For some reason the unit is coming too far forward and slips off the piston and the lip can't get back on.

I checked out the the blowback unit return springs (the two springs on the sides) and they looked fine. I stretched them out but the unit is still coming out too far.

It doesn't look like anything is broken. Maybe I just need to get a stronger spring set for everything.

[Soulfly]

How about you just sell that to me for cheap.. :P

Or, If you wanna ship it up to Edmonton, I should be able to fix it for ya.

PM me.

[SHÖCK]

Originally Posted by Soulfly

How about you just sell that to me for cheap.. :P

Or, If you wanna ship it up to Edmonton, I should be able to fix it for ya.

PM me.

$600 and it's yours :P

I don't know why it's acting like this all of a sudden, the design seems to be flawed because nothing stops the blowback assembly from going so far forward that the lip of the air chamber slips off the blowback piston head at the back and then gets misaligned so it can't return as the lip just jams on the piston head.

I think some stronger return springs should stop this from happening though. Not sure why the stock ones are so weak, it's not a TM afterall

[aznpos531]

I have that problem on my full metal KJ M9 as well. It doesn't happen often but when it does, I just rack the slide and it goes back to normal. Sometimes when I rack the slide slowly, I can hear the nozzle sticking for the first few millimeters, then gets unstuck and makes a very distinct "pop".
I suspect that the outer barrel tilts backwards during cycling and presses on the top of the nozzle and it gets stuck.

[Soulfly]

Why not just order a new rubber for the 'piston'?

Because I think It's supposed to come out of the nozzle, Bleeds the excess pressure and the slide goes forward.

[SHÖCK]

Yeah, it's this piston lid that the nozzle assembly is slipping off of and not being able to slip back onto when the slide goes forward again. After inspecting it, I don't see anything really wrong though. I've lubed it up and it seems to be working better but it's still sticky sometimes.

http://shop.ehobbyasia.com/guarder-e...i-m92f-m9.html

[Soulfly]

Give it a shot!

Maybe grab a new cylinder while your at it?

Once I get my Box-o-parts from KJW, I'll ship you my old cylinder.. Maybe that would help?

[SHÖCK]

Do you guys think it might be magazine overpressure? KJW fill valves are notorious for allow you to overfill a mag.

Then again, these guns are also sold to work on CO2 so it should be able to take a lot of power.

Maybe a 150% recoil and hammer spring upgrade would alleviate this problem? That would kill gas efficiency though, I can get two mags worth out of one fill right now.

How long do you guys fill your mags for?

[SHÖCK]

Regarding the piston lip, I have lubed it up with yellow lithium grease and it seems to be working more smoothly now and while it does still jump out, the grease allows it to pop back in when the slide releases forward.

My main problem now seems to be the gun won't feed every now and then. I can press the trigger over and over again and it will fire but the bb won't actually move out of the feed lip into the hop-up rubber.

Under the nozzle is the pusher that pushes the BB's forward and it seems to work (if it stops feeding, I rack the slide manually). This problem must be related somehow but I can't figure out what is wrong.

I've tried 2 different mags and even sanded the lip of one of them in case that was the issue but I don't think that is is. It must be the nozzle/bb pusher/cylinder that is the cause of all my problems

[Soulfly]

I still say you should get some new stuff, Piston Cap (#23) and Cylinder/Nozzle (#19).
Along with the Cylinder valve (#21).

It sounds like your pistol has the power to push the slide back, but the cylinder isn't sliding back fast enough. Maybe it's binding? Check if you can move it easily with your finger?

[SpikedGhost]

Just sounds to me like the gun has been used A LOT and just like on cars for example, parts wear out (piston lip, and maybe others too in your case) so me too I just say you should get some replacement parts for it. And another thing, you can still get the enhanced springs if you want, but it doesn't sound to me like they are the problem.