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KJW M4

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Does your mag valve move freely and snap back quickly?

yep... its kinda wierd cuz it works just fine in single although not nearly as efficient its still skirmishable. the full auto issue and gas inefficiency plagues all three of my mags from what i can tell... thanks for the advice.

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I'm thinking one of the sears catches and wont release the hammer...busted sear possibly.

 

Have you been running propane/green gas?

 

Fixed that problem, the O ring from the cradle velocity reducer broke and landed under the selector switch/sear. However, now my selector switch is really loose when I put my pistol grip back on. Also, the spring slides all the way inside the hole now, there is nothing giving it resistance, how do Ifix this. Lastly, the selector doesn't click into place, it just moves freely when the grip and spring are installed. Any help is appreciated, thanks!

 

Edit: Fixed it, didn't realize the detent pin for the spring/selector fell out. Was able to find it scouring my carpet on hands and knees.

Edited by nickthebrick65

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Andrew, I'm interested in knowing your thoughts for not using green gas. Thanks.

 

Silicon is not meant to be in the internals of this gun, including the hop and barrel, just messes up stuff. Throws your shots off too much. There are only two things that get lubed on this gun, the buffer tube, and the piston/piston cup.

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Silicon is not meant to be in the internals of this gun, including the hop and barrel, just messes up stuff. Throws your shots off too much. There are only two things that get lubed on this gun, the buffer tube, and the piston/piston cup.

 

thanks. I take it you're using straight propane, which, unfortunately is not available here in Hong Kong.

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hey folks quick question for you. as of late whenever i fire my rifle in full auto i get about 3 or 4 shots off before it just stops working. i have to pull back on the charging handle to get it going before it does the same thing all over. it doesnt chamber the last round before it stopped firing and it acts as if theres no gas in the mag at all. i broke it down to see if there were any problems and i cant find anything that would cause that problem. im lead to believe that its the magazine but i drop some lube in them and to no avail... ontop of that ive noticed that its not as efficient on gas as it used to be. i went from almost 3 mags of bbs to 1 1/2 per fill of gas. now this didnt happen until i had to replace my floating valve assembly. but i dont think it would hinder my full auto functionality. also more often ive noticed that my bolt lock function doesnt work as often.

 

PLease try with 134a gas and see if FA works.

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PLease try with 134a gas and see if FA works.

im not too sure 134 will help... i was doing some more shooting with it and it is just going through gas like a madman. i was thinking perhaps its the magazines but all three of my mags are suffering from the same problem at once... i dont think so. would you guys recommend taking the magazines apart.

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Doesnt sound like mags are the problem. Please give us your current setup for the gun. Gas use, temperature during testing, aftermarket parts installed if any, etc. no info is too much info.

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Doesnt sound like mags are the problem. Please give us your current setup for the gun. Gas use, temperature during testing, aftermarket parts installed if any, etc. no info is too much info.

at the moment im running your tightbore and bcg extension... about 3 weeks ago i installed a new "stock" floating valve assembly, the temperature of my last two tests were around 70-75 degrees fahrenheit. as far as rounds go i put about 40 rounds through it between two mags. the first mag went through 30 rounds and since the bolt-lock didnt engage i put about 5 more rounds through it before it was empty on gas. the second magazine i didnt get half way through it before the gas was gone. i was testing my full auto function throughout this test but due to the current issue im having id only get 3 shots off before it would stop cycling. wherein id charge the rifle then continue on single. which is the only fire-mode it works in without stopping. i notice today when firing on semi theres alot of gas spewing from the the barrel and its not just one or two shots its pretty consistent throughout the cycling of the magazine. the bolt lock function only seems to be failing with one of my three mags, but when my bolt locks back ive noticed gas seeping from the chamber aswell. thanks, for helping. Edited by senators2904

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im not too sure 134 will help... i was doing some more shooting with it and it is just going through gas like a madman. i was thinking perhaps its the magazines but all three of my mags are suffering from the same problem at once... i dont think so. would you guys recommend taking the magazines apart.

 

Definitely sounds like a floating valve problem. Lack of a good seal is causing gas inefficiency, which is causing your gun to short stroke. This is causing the choppy and erratic full auto and is not allowing your bolt catch to engage consistently. Same problem happened to me.

Edited by Mental Medic

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certainly sounds like a solution... what i'll do is run it without the floating valve to see if i can empty a mag without stopping. if so then i either have to learn how to put the stock floating valve on properly or make a break for Travis' velocity reducer... its really weird that it would start malfunctioning on me like that, aside from testing it that game last week was the only use the rifle got. i dont think i put 300 rounds through it after installing that new valve assembly. ho hum. thanks for tip man.

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Without the valve you are going to get terrible gas efficiency. Id first look to see that your valve is working in the first place. If you stick a pen or something in the piston cup with it removed from the piston can you press the valve down? Is it moving freely? Does the spring push it back easily? If its sticking Im reasonably sure thats your problem.

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If its a butane mix it won't work well.

 

I'm not sure of the composition of the portable gac canister but it's the cheapest gas around here other than Green gas. There's also straight 134a and R22 which I'm also making adaptors for testing for an alternative to Green/Top gas.

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Did you check the O-ring on the floating valve? I was having bad gas consumption yesterday because the O-ring on my velocity reducer broke off.

 

That should not be it. You can run the floating valve without an oring or any spacers and you should still get 2 mags worth at 70*

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im not too sure 134 will help... i was doing some more shooting with it and it is just going through gas like a madman. i was thinking perhaps its the magazines but all three of my mags are suffering from the same problem at once... i dont think so. would you guys recommend taking the magazines apart.

 

In my case, temps are 33C/92F, humidity 90+% and my gun internals are all factory parts. If I use Top gas, my FA will not work. If I use 134a, FA works fine. I have manually checked the FA sear and by working the CH back and forth while pressing teh trigger, I can hear the BCG trip the sear. I suspect in my case its a timing issue due to excessive BCG speed unless my understanding of FA operation is wrong. So, right now I'm making a heavier buffer, sourcing a stronger buffer spring and trying them on my gun to try reducing the BCG speed. I will report on my test results.

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Piston, extension and reducer all fitted. Finally I can get some skirmish action :D

 

Only really needed the reducer to be skirmish ready as it was 440 on GG now 330 with the thickest spacer + one of the lowest thickness ones.

Edited by weekenny

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Piston, extension and reducer all fitted. Finally I can get some skirmish action :D

 

Only really needed the reducer to be skirmish ready as it was 440 on GG now 330 with the thickest spacer + one of the lowest thickness ones.

 

the cradle extension and piston are an essential in my mind. The extension saves your receiver and the piston adds some seal and FA smoothen up a bit. You'll see what I mean when you lay into a mag in FA

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Having a new CQB with the modified buffer lock the extension isn't a necessity.

 

In fact during fps testing I've noticed the bolt lock isn't as consistent with the extension fitted so I've removed it again.

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Was testing inside so temperature wasn't an issue and was only shooting semi. Since I was only testing I never had more than 4-6 bbs loaded and rapid semi shots didn't lead to a lock. Even when empty if I hit the release I could shoot rapid semi and not have it lock.

 

As soon as I noticed the issue I removed the extension and repeated the same tests and it locked as it should.

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