Tanio Koba / KJW M4 GBBR Basic Information and FAQ

George Burdell · May 24th, 2011, 18:19

Quote:

Originally Posted by Nova_Dust

Dial the hop up back to original position first.

Remove the flash hider (the thread is counter-clockwise, so turn it clockwise to loosen it, and some models have a small hex screw at the bottom of flash hider), front sight (punch out two pins), hand guard, gas tube and get to the delta ring. Unscrew it (clockwise thread, so turn it counter-clockwise) until you get the entire front barrel assembly out. The inner tube should fall right out. Get ready to catch it, don't just let it fall right to the floor.

The hop up rubber is sandwiched by 2 metal pieces and secured with a metal ring/tube thingy. Pull that metal ring/tube (towards the front) and the 2 metal hop up piece will just come apart.

You can access the hop up rubber now. The notch on the inner tube matches to the nib of the hop up rubber.

Assembly is reverse of the procedure. You may notice there are two small grooves on the inner tube, one near the hop up and one near the front of the inner tube. I am not exactly sure what they are for but I put two small o-rings on there which help to stable the inner tube. Or two revolutions of scotch tape will do the same job. You will feel slight tightness when you reinsert the inner tube if you did this mod. I did this cause when I changed to 363mm inner tube, I noticed slight play hence I did the mod.

Hope this helps.

Cheers

I am having trouble removing that brass ring, did they use loctite?

Long_Bong · May 24th, 2011, 19:02

Hi,

I m considering doing this mod, anyone has tried it that could post a shopping list with material spec (length etc)

Thanks

Quote:

Originally Posted by HKp30

Top Down Hop-Up adjust

Barrel shim using metal sheets, you can see it fully wraps around the barrel for a very snug fit. Thickness of metal sheets needed may be different depending on your barrel.

bean · May 24th, 2011, 19:09

Stupid Cobra making me sell my gun to get one of these. Looks like in a few months I shall have one of these.

Cobrajr122 · May 24th, 2011, 20:10

=D

NVC · May 24th, 2011, 20:57

You will need this metric tap kit. I used the 4mm tap one with 4M hex screw.
http://www.princessauto.com/workshop...oy-tap-die-set

A drill press makes it alot easier.. USE cutting fluid/oil when drilling and while doing the tap threading and go slow and straight. This mod is worth it if it is done right.

Long_Bong · May 24th, 2011, 23:20

Thanks a lot sir

What length of screw did you use? Is 4M a length?

Quote:

Originally Posted by NVC

You will need this metric tap kit. I used the 4mm tap one with 4M hex screw.
http://www.princessauto.com/workshop...oy-tap-die-set

A drill press makes it alot easier.. USE cutting fluid/oil when drilling and while doing the tap threading and go slow and straight. This mod is worth it if it is done right.

Long_Bong · May 25th, 2011, 10:28

17 mm is the length of the screw for those going foward with this project

Nova_Dust · May 26th, 2011, 07:33

Quote:

Originally Posted by George Burdell

I am having trouble removing that brass ring, did they use loctite?

Not with mine.

Sometimes the brass ring could become a bit hard to remove. What I did last time was using a pin tool (not sure what it is called, a screwdriver-like tool with a pointy thing at the end), place it at the base of the brass ring and tap it with a hammer slowly until you get enough gap to fit a flat head screw driver in the gap, then tap it again slowly until you can get enough hand grip to remove it.

Hope it helps.

NVC · May 26th, 2011, 12:51

I have some pictures on a 2nd upper I did this mod too I will post later. Also I used 2 length's of hex screws 17 and a 20mm. The tap I used was a 4Mx0.7 from the kit.

Here some pics

I did my 2nd tap about 2-3mm towards the delta ring threads so that the hex screw push's exactly center on the Ra-tech hopup nub then HKp30 when he tapped it in the center of the rail. 3rd pic looks off but its the angle of how I took the picture. Both ways work fine. Hope this helps everyone.

bean · May 27th, 2011, 11:58

I am seriously considering doing this mod when I get mine. Do you have any before and after pictures of the consistency achieved with this mod?

NVC · May 27th, 2011, 12:30

No I have not done a controlled range test yet. But when I first installed Ra-tech custom cut 300mm TB an blue hopup rubber, cradle x-piston, velocity reducer approx 380-400fps(.2's) with max hopup setting with KSC's .30. At a local field I did a brief test would get 70 feet and the bb's would loop down. I was so disgusted in the range I put the gun back in car and was debating to sell it. I have a 2nd complete upper as well chrono at stock 450ish fps stock barrel and hopup and the range was the same. I dont know if I got 2 lemon's or how other people are saying their range is good or they must be used to using guns with very crappy range, lol. I can say that the range double easier even more.

Long_Bong · May 27th, 2011, 12:54

Did it yesterday, the hop up now work very well

Thanks NVC!!!

bean · May 27th, 2011, 12:55

Cool I will definatly have to give this a go when I get mine.

Long_Bong · May 27th, 2011, 12:59

2 quicks one,

I m looking to magpull mine, has anyone attemped to install those:

http://www.redwolfairsoft.com/redwol...rms_M4_GBB.htm

http://www.redwolfairsoft.com/redwol...ries_Black.htm

Thanks

George Burdell · May 27th, 2011, 14:25

How do you find the exact point where you should drill into your gun for the grub screw mod?

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May 24th, 2011, 20:10	#424
Cobrajr122 2 Cent Tactical Trader rating Join Date: Apr 2006 Location: NB	=D __________________ www.2centtac.com F i n d - a n - A g e - V e r i f i e r

May 24th, 2011, 20:57	#425
NVC Trader rating Join Date: Jul 2009 Location: Edmonton	You will need this metric tap kit. I used the 4mm tap one with 4M hex screw. http://www.princessauto.com/workshop...oy-tap-die-set A drill press makes it alot easier.. USE cutting fluid/oil when drilling and while doing the tap threading and go slow and straight. This mod is worth it if it is done right. __________________ Custom Kydex Holsters - pm me for details

May 25th, 2011, 10:28	#427
Long_Bong Trader rating Join Date: Dec 2007 Location: Canada	17 mm is the length of the screw for those going foward with this project __________________

May 24th, 2011, 19:09	#423
bean Administrator Trader rating Join Date: Oct 2004	Stupid Cobra making me sell my gun to get one of these. Looks like in a few months I shall have one of these.

May 26th, 2011, 12:51	#429
NVC Trader rating Join Date: Jul 2009 Location: Edmonton	I have some pictures on a 2nd upper I did this mod too I will post later. Also I used 2 length's of hex screws 17 and a 20mm. The tap I used was a 4Mx0.7 from the kit. Here some pics I did my 2nd tap about 2-3mm towards the delta ring threads so that the hex screw push's exactly center on the Ra-tech hopup nub then HKp30 when he tapped it in the center of the rail. 3rd pic looks off but its the angle of how I took the picture. Both ways work fine. Hope this helps everyone. __________________ Custom Kydex Holsters - pm me for details Last edited by NVC; May 27th, 2011 at 11:05..

May 27th, 2011, 11:58	#430
bean Administrator Trader rating Join Date: Oct 2004	I am seriously considering doing this mod when I get mine. Do you have any before and after pictures of the consistency achieved with this mod?

May 27th, 2011, 12:30	#431
NVC Trader rating Join Date: Jul 2009 Location: Edmonton	No I have not done a controlled range test yet. But when I first installed Ra-tech custom cut 300mm TB an blue hopup rubber, cradle x-piston, velocity reducer approx 380-400fps(.2's) with max hopup setting with KSC's .30. At a local field I did a brief test would get 70 feet and the bb's would loop down. I was so disgusted in the range I put the gun back in car and was debating to sell it. I have a 2nd complete upper as well chrono at stock 450ish fps stock barrel and hopup and the range was the same. I dont know if I got 2 lemon's or how other people are saying their range is good or they must be used to using guns with very crappy range, lol. I can say that the range double easier even more. __________________ Custom Kydex Holsters - pm me for details

May 27th, 2011, 12:54	#432
Long_Bong Trader rating Join Date: Dec 2007 Location: Canada	Did it yesterday, the hop up now work very well Thanks NVC!!! __________________

May 27th, 2011, 12:55	#433
bean Administrator Trader rating Join Date: Oct 2004	Cool I will definatly have to give this a go when I get mine.

May 27th, 2011, 12:59	#434
Long_Bong Trader rating Join Date: Dec 2007 Location: Canada	2 quicks one, I m looking to magpull mine, has anyone attemped to install those: http://www.redwolfairsoft.com/redwol...rms_M4_GBB.htm http://www.redwolfairsoft.com/redwol...ries_Black.htm Thanks __________________

May 27th, 2011, 14:25	#435
George Burdell Trader rating Join Date: May 2011 Location: Toronto	How do you find the exact point where you should drill into your gun for the grub screw mod?

Tanio Koba / KJW M4 GBBR Basic Information and FAQ

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