Tanio Koba / KJW M4 GBBR Basic Information and FAQ

[IggysPiggy]

yes its simple pull bolt out of receiver. now look for the fake screw not quite halfway back, punch the PIN out of the bolt (not the fake screw but the pin thats closest to it). now there is no spring tension on the nozzle/piston asm. the little plastic rectangle on the side needs to be removed next, all you do is take a small flat head screwdriver and from the inside of the bolt push the back of the rectangle out. it will push out slightly now you have to slide it towards the back of the bolt and gently push out with screw driver. the piece is a guide/retainer and is about twice the length that you actually see. now the whole nozzle/piston asm will come right out. the rest of the tear down is simple theres a small pin at the back that holds the piston cup asm on, push out gently and put to side. nothing will have come off at this point as there is on last screw/pin to remove. this is the one halfway down the nozzle that holds the return spring in as well as the floating valve. remove and it is all apart.

[LocoYokoPoco]

Originally Posted by IggysPiggy

yes its simple pull bolt out of receiver. now look for the fake screw not quite halfway back, punch the PIN out of the bolt (not the fake screw but the pin thats closest to it). now there is no spring tension on the nozzle/piston asm. the little plastic rectangle on the side needs to be removed next, all you do is take a small flat head screwdriver and from the inside of the bolt push the back of the rectangle out. it will push out slightly now you have to slide it towards the back of the bolt and gently push out with screw driver. the piece is a guide/retainer and is about twice the length that you actually see. now the whole nozzle/piston asm will come right out. the rest of the tear down is simple theres a small pin at the back that holds the piston cup asm on, push out gently and put to side. nothing will have come off at this point as there is on last screw/pin to remove. this is the one halfway down the nozzle that holds the return spring in as well as the floating valve. remove and it is all apart.

Thanks! I didn`t even notice the pin haha.

The piston head rubber on my bolt was shredded, but i sucessfully replaced it with the RAtech rubber. Also, the spring that held the pistoncup to the bolt broke after a skirmish. I also replaced it with the pistoncup spring from the original bolt.

[IggysPiggy]

Huh so maybe a heads up on these ive seen three cases of shredded piston cups and broken loading nozzle spring now so ppl tear these down upon purchase and inspect, all three had less then a hun rounds.

[beanie]

My gun has been having some issues keeping a steady rate of fire on full auto. I have a video so you can see what I mean, problem starts at 9 seconds. M4 - YouTube.
Any ideas/anyone else had this issue?
Running with a unmodded version 2 bolt. The problem was happening with the V1 as well.

[PHARAOH]

Originally Posted by beanie

My gun has been having some issues keeping a steady rate of fire on full auto. I have a video so you can see what I mean, problem starts at 9 seconds. M4 - YouTube.
Any ideas/anyone else had this issue?
Running with a unmodded version 2 bolt. The problem was happening with the V1 as well.

In your video it is clear that your rate of fire is slowed due to your bolt freezing up....propane is cold and a sustained firing like that will freeze the bolt.

[Cj Radge]

Hi Beanie, that is a known limitation of all GBBr. Propane is cold as Pharaoh said. Sustained rate of fire like that will definitely give that result. In your video, I believe its not the bolt that freezes but the magazine valve.

GBBrs have 30 rounds only so you should not experience that in the field because you wont be firing like that in a single mag. In fact, KJW Tanio Koba system is good enough to sustain continous 30 rounds of fire without freezing up. Some other system cannot even sustain continous 30 rounds of fire, they freeze up quickly.

[jeffmorton]

Hey guys, that video of beanies is perfect. I have the exact same issue, except instead of 9 seconds in its almost immediate. Like it fires maybe 2 or 3 rounds then slows down and usually dumps all the gas...
Any ideas or suggestions for that?

[George Burdell]

Originally Posted by jeffmorton

Hey guys, that video of beanies is perfect. I have the exact same issue, except instead of 9 seconds in its almost immediate. Like it fires maybe 2 or 3 rounds then slows down and usually dumps all the gas...
Any ideas or suggestions for that?

Is the cap for your buffer tube screwed in fully? If it's not, it causes problems.

[jeffmorton]

The cap is screwed on as tight as it will go.

[PHARAOH]

hey guys, im having a problem with the "last shot hold-back" feature on my KJ. basically after my 30th shot the bolt doesn't hold back and will continue to fire blanks.

has anyone else ran into this, and if so what can be done to fix it.


thanks

[IggysPiggy]

Its the little tab on the side of the mag, they wear out after use tho so if you have it in the right position and still doesnt hold the bolt open then the tabs probably worn down or the catch is worn down.

[Cj Radge]

Pharoah, make sure the buffer tube does not wobble. Tighten it up. its a known issue in KJ m4 GBBr which has a very easy fix of just tightening the buffer tube.

Let us know. Thanks

[Saberwing]

Broke my V1 bolt at Adrenaline on Sunday. Ordering a V2 bolt tonight. CJ, I'll be contacting you soon.

[jmacs]

was wondering if anyone had a solution to a v2 KJW / TK M4 open bolt CQBR basically my bolt catch is not working, well it does sometimes but not everytime.. its REALLY stiff and slows me down when i need to change my mag causes problems on the field..

[LocoYokoPoco]

Originally Posted by jmacs

was wondering if anyone had a solution to a v2 KJW / TK M4 open bolt CQBR basically my bolt catch is not working, well it does sometimes but not everytime.. its REALLY stiff and slows me down when i need to change my mag causes problems on the field..

Mine does the same thing.