KJW M4 gbbr

[Charlot1405]

Hello everyone,

I am having a lot of trouble with an m4 i bought about 6 months ago. I must say that I bought it completely destroyed, and paid a very low price for it (basically paid for the mags and gun was free with it). I wanted to rebuild in order to understand gbbrs more in depth, and I think I got more than what I bargained for.

So here is a photo of the airsoft:


When I first tried it, it did not shoot. It was not a big surprise, since there was no bolt carrier. When th one I ordered finally arrived, I was happy to hear it shoot. But the problem is that the trigger does not seem to cycle completely. Also, when I try to turn the selector to auto, the m4 discharges, and blocks before arriving to auto. Here is a video of what is happening:

https://vid.me/0WGz

So after separating the receivers, this is what I can see. Now I know the quality is not very good, since it was hard to shine it inside the lower, but here is what I understood. The selector seems to get stuck under the trigger assembly instead of over, which causes the trigger group to raise, and therefore, shoots. I have disassembled and reassembled it countless times and have never been able to change that. Here is the video of what is happening:

https://vid.me/YwS1

For the problem of the trigger not resetting, I am afraid I simply have no clue of what happens, and therefore cannot show anything. Although, I can assume that this problem is linked to the selector and the trigger group. Here is a picture of what the internals look like.



But the problems do not stop here, as I have other external problems (less important IMO). First of all, the handguard is crooked, which can (probably) easily be fixed by getting my hands on one of these handguard tools. The second problem comes from the buffer tube, which seems snapped in two. It would be easy for me to remove it and check exactly which pieces are broken, only the screw which prevents the tube from being removed is stripped. Here are the pictures and the video of the buffer tube:





https://vid.me/0WSz

Thank you all for your help, if you need more pictures or anything I will provide them, feel free to ask!

[Kungpow]

Originally Posted by Charlot1405

Hello everyone,

I am having a lot of trouble with an m4 i bought about 6 months ago. I must say that I bought it completely destroyed, and paid a very low price for it (basically paid for the mags and gun was free with it). I wanted to rebuild in order to understand gbbrs more in depth, and I think I got more than what I bargained for.

So here is a photo of the airsoft:


When I first tried it, it did not shoot. It was not a big surprise, since there was no bolt carrier. When th one I ordered finally arrived, I was happy to hear it shoot. But the problem is that the trigger does not seem to cycle completely. Also, when I try to turn the selector to auto, the m4 discharges, and blocks before arriving to auto. Here is a video of what is happening:

https://vid.me/0WGz

So after separating the receivers, this is what I can see. Now I know the quality is not very good, since it was hard to shine it inside the lower, but here is what I understood. The selector seems to get stuck under the trigger assembly instead of over, which causes the trigger group to raise, and therefore, shoots. I have disassembled and reassembled it countless times and have never been able to change that. Here is the video of what is happening:

https://vid.me/YwS1

For the problem of the trigger not resetting, I am afraid I simply have no clue of what happens, and therefore cannot show anything. Although, I can assume that this problem is linked to the selector and the trigger group. Here is a picture of what the internals look like.



But the problems do not stop here, as I have other external problems (less important IMO). First of all, the handguard is crooked, which can (probably) easily be fixed by getting my hands on one of these handguard tools. The second problem comes from the buffer tube, which seems snapped in two. It would be easy for me to remove it and check exactly which pieces are broken, only the screw which prevents the tube from being removed is stripped. Here are the pictures and the video of the buffer tube:





https://vid.me/0WSz

Thank you all for your help, if you need more pictures or anything I will provide them, feel free to ask!

It sounds like the trigger and trigger sear are slipping causing the gun to fire once the auto sear is engaged. The trigger resetting issue is a trigger and trigger sear issue as well. Could it be that the parts are worn out? It seems that the auto sear could be installed incorrectly. There are a few guides on removing stripped screws. Plus I think Canadian Tire sells a stripped screw repair kit.

This video may help you understand how a select fire AR works

https://www.youtube.com/watch?v=WtGZBL5BmZE

[Charlot1405]

Thank you very much. Because of this great video I was able to notice that the springs in the trigger were not working well anymore, and I replaced them with other springs, and now the m4 shoots both semi and auto without having to push the trigger forward! Thank you again!

I will continue working on the eterior now!

[Tuzi]

Ok, I've resisted for a very long time, but I need to finally say it...
See that yellow handled "screwdriver" at the top right? Unless you're using it as a target for firing against, get rid of it.
One of your stated challenges is that the screw in the buffer tube is stripped.
No one here seems to realize the (+)"crosshead" screws in 99% of all airsoft products are NOT Phillips head screws! Every post I've read on this and other related forums suggest no one knows.
Just about everything produced outside of the US, that has a (+) head is either a Pozidriv (which I mention only because I fear the same ignorance to that unique shape, as it's not actually a crosshead at all), or JIS.
Most of the better quality screws will have a proper designation, which is the single dot in one of the quadrants. Phillips cross head screws came out of the time of the Flintstones when there were no intelligent tools or skilled assembly line workers... they were designed to cam-out. Meaning, the very use of a Phillips head driver, is going to destroy the head of the screw...as engineered. JIS (japanese industrial standard) cross head screws and drivers are designed NOT to cam out and thus requires some intellect by the one holding the tool.
Most of our culture over here is with the mind set, "make it work"... people get the idea of applying more downward pressure, or using "precision" tool sets to get the job done...
I hate continually seeing stripped screws, and get even more upset when I find out the guns came from other "reputable gun docs". With all due respect, the guys are good at math, and theory with physics... but using the right tools for the job... is like walking before running.

Seriously, if your local shop or doc doesn't know or have a JIS crosshead driver, walk away.