Problem with auto firing on a KJW M4 GBB

[jeffmorton]

Hi guys,
New to the site, and hate that my first post is a problem but I'd like to get some input possibly.
I bought a KJW M4 CQB GBBR recently, my first airsoft gun. It works almost flawlessly when firing in semi mode. However when I switch to auto I encounter a few different issues.
1) Some times it will fire approx 2 or 3 shots, then the bolt jams back and all the propane from the clip is exhausted out the side and/or the barrel.
2) Sometimes it does not jam but instead just stops firing. On these occasions if you pull back the charging handle it will fire one shot then stop again. Almost as if it's switched itself to semi-auto? You must pull back the handle each time though, the trigger remains dead after each shot ie doesn't reset.

This has occurred right from the second I got the gun. It has had silicone grease applied to the bolt. Same issues. Was cleaned off and tried with 1.5 wt silicone oil, ultra slick synthetic grease, and silicone spray lube, all with similiar results.

I'm not sure if this is possibly an issue with the mags not being properly charged with propane, too much lube, not enough lube, or some other issue.
I used the shelledpants cleaning guide I found on here for the general cleaning/lubing guideline.

I'm pretty new to these things, so while I've been reading and searching a lot, I may not understand what certain parts are, methods, etc so please try to keep any answers relatively simple!

One other thing, this is apparently the version 2 bolt in this gun if thats much relevance. Thanks for any advice or suggestions.
Jeff

[jeffmorton]

No random theories, guesses, anything? At least the semi mode works I guess.

[jeffmorton]

Went out again tonight. Tried to pay attention more to what the gun was doing. Temp was about 15 C and very damp, had rained a couple hours earlier.
Fired a couple shots off in semi first, everything works fine. Switched to auto and it fired about 2 or 3 nicely, then you can feel and hear it start to lose power. As this happens you can also notice a larger puff of propane coming out the bolt opening, and also out the end of the barrel. Within a matter of 4 or 5 shots, it powers out completely and wont even fire. Almost acts like it's out of propane. However, you can switch it back to semi-auto at this point and it will fire off the rest of the magazine.

Put in second magazine, and it fires sluggishly right from the start, and then after 8 or 10 shots it dumped the rest of the propane out the bolt. Third mag and then subsequent refills of the 3 all result in either sluggish, low powered firing, jamming, or dumping the gas out of the mag.

I don't know enough about these things, but it's like it's allowing too much of the propane to escape out the bolt opening, and not allowing the bolt to cycle quickly enough to shoot. I'm not sure if thats possible even?

Does anybody have any theories? Maybe things I can try to to help you narrow it down? This thing is getting so frustrating I might just run it over a few times and cut my losses.

Couple random questions. When the bolt cycles, should the plastic nozzle inside/part of the bolt stay wedged in the rubber by the hop-up for part of the travel, or should it freely pop out the second the bolt starts going back? Sometimes mine is tight enough it stays in briefly then snaps back, other times it all moves back as one piece.

And for filling these magazines using the small Coleman propane bottles, I have been holding it on until I can't hear gas flowing anymore, usually in the 15 second or more range. Any idea if these just may not work well to fill the magazines, maybe a BBQ style tank and hose would be better suited?