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KJW M4

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As you guys are modifying your outer barrels please remember that the measurements Raven1 and I posted way back when were for just one type of outer barrel. Ive done a lot since then of many different brands and they have all been different. Some have required the bore be enlarged while others haven't. Some needed the depth of the bore shortened instead of lengthened.

 

My advice to those doing this mod is to get a set of digital calipers and take your time planning out your cuts.

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Thanks to the guys putting in all the testing and reading this thread, along with others, my KJW is inbound.

Very pleased to see the reliability results that have been chronicled.

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Thanks Johnyew, that gives me a bit clearer idea about how to do this. T_hum, you bring up a good point. It will mostly just be trial and error. I'll report about how it goes. It'll take about 7-10 days for the barrel to even arrive here at my place, so it will be a while still.

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UPDATE: :(

 

after about 3 weeks of having my rifle i am indeed happy with its reliability, now its accuracy on the other hand is another story. My rifle actually suffers from the hop-up issue that others have been having in the thread, and while utilizing the shrink tubing fix it does work as far as making the hop-up effective cause i can now over hop my .25g bbs (so there is progress) but when i try for a more accurate setting in the hop-up dial i get alot of inconsistency and curving to the left, now my bbs do fly straighter for a longer distance but inevitably curve toward the end vs flying straight out. The only time i dont get curving is when im over hopping the bbs so they fly straight up at around 50ft. i wonder if getting a heavier gram like a .28g or even a .30g would straighten out the trajectory on the higher hopup setting. i still have yet to get the longer tightbore for it. is there any advice you folks could pass along to me. Thanks in advance folks

Edited by senators2904

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typically curving left or right is caused by a mis-aligned hop rubber, or in your case perhaps un-even heatshrink thickness, remember if you are applying hop not to the direct top of the BB then it will have a diagonal spin and curve off to the left or right at the end.

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@ whiteHawksan: from what i can tell the thickness of the shrink tubing should be good as far as thickness. i did use two layers. one thing i did notice about the hopup is that when i turn the dial to set it in a higher groove on the wheel the arm itself wobbles from left to right... i also noticed that when theres a bb in the chamber waiting to be fired theres a bit more pressure on the hop-up wheel cuz its a bit harder to to turn vs the chamber being empty.

 

one thing just recently came to mind about eveness, when the hopup is in effect how much of the arm itself does the bb touch im wondering a bit cuz i thought it was just the tip of the arm. if thats not the case then perhaps it could be the way i applied the two pieces of shrink tubing. i used the same size tubing and it was already tight slipping the first piece on the arm when, it came time to put the second piece on it covered the tip more than it needed too but i was off maybe a mm from where the first piece was attached. now i remember another guy using the same 2 pieces of shrink tubing idea i was just wondering if he shrank the first piece before putting on the second or did he get 2 different sizes slipped em on over each other then cut them to size and shrank them.

 

THANKS FOLKS

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ive emailed like twice over a month still no response

 

I emailed in the evening and had a response by Clare in the morning.

 

Be sure you're using the correct email address, state "Parts Quote Please" in the Subject line of the email and be sure to include ONLY the Part #s In The Subject line of the email.

 

In the main Body of the email state your parts and quantity, followed by your address so they know how to calculate Shipping. Then Wait for the response email and finish it with a PayPal trans action.

 

Subject Line

 

Parts Quote Please - M1 - M7 - M9 - M12 - M14 - T3 - T4 - T5 - T6

 

Main Body

 

Clare,

 

Hello, I Hope you have been healthy and happy!

 

I need a quote for magazine parts please.

 

Qty (1) - Part # T3

Qty (1) - Part # T4

Qty (1) - Part # T5

Qty (1) - Part # T6

 

Qty (3) - Part # M1

Qty (3) - Part # M7

Qty (3) - Part # M9

Qty (4) - Part # M12

Qty (3) - Part # M14

 

Shipping

Raven1

XXXXXXXXXXXXXXX

XXXXXXXXXXXXXXX

 

Normal Shipping Please.

 

Thank You Clare For Best Service!!

 

-Raven1

 

The Correct Email Addy -- kjworks@ms47.hinet.net

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I have to say this is the most fun weapon that I've ever used for airsoft, even beats thermobarric mortars.

 

Did have a little trouble with mags feeding at first, but it disappeared after I disassembled them. just need to get somewhere with a bit more range than 10m in the garage :(

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Thanks Johnyew, that gives me a bit clearer idea about how to do this. T_hum, you bring up a good point. It will mostly just be trial and error. I'll report about how it goes. It'll take about 7-10 days for the barrel to even arrive here at my place, so it will be a while still.

 

As Travis said, it's wise to get a digital caliper, which I have and measure the hop up chamber placement within the outer barrel between the orginal KJW and your own outer barrel. The critical dimension would be the depth of the hop up chamber, which if not correct, the hop up arm won't depress against the bucking.

Edited by johnyew

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....... now i remember another guy using the same 2 pieces of shrink tubing idea i was just wondering if he shrank the first piece before putting on the second or did he get 2 different sizes slipped em on over each other then cut them to size and shrank them.

 

THANKS FOLKS

 

Both pieces were of the same size and I shrunk the first piece before putting on the second piece which was also shrunk.

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Look back over the past 10 or so pages. Some guys have resorted to using heat shrink tubing on the hop arm to make it slightly thicker. Maybe the KJW needs an enhanced hop arm. Ill look into it.

 

Travis, not sure if you have analysed the hop up arm yet, but if you are able to design a unit so that it does not have any side by side movement at all, then you have another winner on your hands for us KJW owners.

 

For me, I'm contemplating drilling/tapping a hole right above the hop bucking and using a grub screw to make the adjustments and get rid of the hop arm totally.

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-johnyew

 

thanks man i appreciate it has your hop up been consistant.

im really contemplating adding one more piece i have noticed that the side to side movement has been reduced. its funny cuz it seems that when ever i lock the arm into a notch the hopup doesnt seems to change no matter what setting i have it on. it kinda sucks cuz it hasnt been warm here lately and i cant get out to test it.

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thanks Raven i'll try that, just to clarify all i needed was the magazine spring, recoil buffer spring and recoil buffer?

 

And i recieved Thums parts (TB,Extension,piston,valve) in today put them on wasn't hard. the extension i had to put some time into it, had to hammer it in to get the receiver to close.

 

When i first got the gun i only fired it about 6-9 magazines in door about 10 - yards away. it shot good no issues, accurate at that distance.

 

Fired it again outside today 80ish temp, on the valve i put the largest spacer and just the oring.

 

on my first magazine i had a lot of miss-feeds, after the first initial magazine no miss-feeds afterwards. but what i started getting was the bolt not locking back all the time, like once every other magazine. So i definitely need the parts from KJW. MY m4 is #80.

 

accuracy was interesting, most shots shot true and had QUITE a few flyers BUT... THE BAG OF BBS I WAS USING IS A MIX OF 0.25 AND 0.20 ELITES, AND PFORCE. so once i get some 0.25 airosft elites and 0.28 to test not paying much attention to the consistency, i wasn't entire sure hopup adjustments were making any big improvements only a few over hoped with the hopup all the way up.

 

all and all still a step up from my WE, i just need to chrono now.

 

and thanks Travis for the parts and the good shipping. im glad you packed the TB the way you did.

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Ill take a closer look at my hop-up assembly. When I looked a few days ago I didn't see any significant side to side play or wobble.

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Ill take a closer look at my hop-up assembly. When I looked a few days ago I didn't see any significant side to side play or wobble.

 

The hop bucking has a raised indent where it contacts the arm. If you can make one that has an inverted 'cup' on the arm end and covers the bucking indent, hoping it would prevent any lateral movement of the arm.

 

ETA: Another thought, if you can make the end of the arm with an inverted 'V' cut that stradles the bucking's raised indent, potentially you would not have any lateral movement of the hop arm.

Edited by johnyew

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-johnyew

 

thanks man i appreciate it has your hop up been consistant.

im really contemplating adding one more piece i have noticed that the side to side movement has been reduced. its funny cuz it seems that when ever i lock the arm into a notch the hopup doesnt seems to change no matter what setting i have it on. it kinda sucks cuz it hasnt been warm here lately and i cant get out to test it.

 

My hop up works about 7 out of 10 shots. I also noticed when adjusting hop is to let it 'settle' somewhat by at least 4-5 shots before making the next adjustment. Certainly the adjustment isn't the same as our AEGs in that the effect isn't always immediate.

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@ TheProdigy

 

Correct, magazine follower spring, Buffer and Buffer spring will take care of the bolt not locking back every time. You are also a part of a small group who is having mis feeds due to the magazine follower spring. Once you change that out you'll be feeding BBs into the hop up fine.

 

 

As for everyone having hop up issues, to be honest I have not experienced any hop up issues with my gun. I did take great care to use the factory outer barrel so that my inner barrel / hop up assembly would be as close to KJW Spec as possible.

 

I have noted when assembling both halves of the hop up, when sliding on / installing the brass locking ring one half may come out of alignment with the other half. Causing a slight distortion (torsional twist) on the hop up bucking, I did have to re-assemble to make sure the assembly was correctly put together.

 

Other than that my hop up has been working great, only set it to forget it type of use,,,

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