t_hum Posted November 3, 2010 Report Share Posted November 3, 2010 True. But mine as worked flawless for over a year. And my part #16 has been in other guns with no positive effect. Odd... Quote Link to post Share on other sites
Kai_Wolf Posted November 3, 2010 Report Share Posted November 3, 2010 When I had my older upper, my hop up was great. The new one I have (given to me) has almost no hop on any setting. It is strange. Hopefully one of these parts can be isolated as the culprit. Quote Link to post Share on other sites
DesertFox Posted November 4, 2010 Report Share Posted November 4, 2010 Does it click every setting? Frankly I think my concept is sound. the lower the hop up dial sits the more it engages the hop up arm, hence more hop up. Quote Link to post Share on other sites
t_hum Posted November 4, 2010 Report Share Posted November 4, 2010 The theory is ok but I don't get how swapping part 94 causes that the happen. Isn't there a limit to how low you can mount the wheel before it hits the receiver? Quote Link to post Share on other sites
DesertFox Posted November 4, 2010 Report Share Posted November 4, 2010 the narrower part of part #94 goes up into the hop up dial, so when you install the screw that holds it together it, it is stopped by the narrow part. If the height of the narrow part is shorter then you could screw in the hop up dial in more situating it lower. At least thats what I think let me know if it makes sense. Quote Link to post Share on other sites
t_hum Posted November 4, 2010 Report Share Posted November 4, 2010 Yeah. Makes perfect sense. So is the new 94 shorter? Quote Link to post Share on other sites
DesertFox Posted November 4, 2010 Report Share Posted November 4, 2010 I don't think so. I put the new and old side by side and they seem identical. Which lead to believe it was my part #16. I guess we won't know for sure until I get some calipers. Quote Link to post Share on other sites
JLiu Posted November 4, 2010 Report Share Posted November 4, 2010 So I removed the grub screw from the flash hider, but when I try to unscrew the flash hider counter clockwise, all I managed to do was strip the threads. It's still firmly attached somehow. Can anyone think of a solution? (I hope I'm not screwed.) Quote Link to post Share on other sites
tome Posted November 4, 2010 Report Share Posted November 4, 2010 Anyone else not get any reply at all from KJW for parts, or is it just me?? Â I've gotten a reply but it's been about 2 weeks since I emailed her. Quote Link to post Share on other sites
GismoBE Posted November 4, 2010 Report Share Posted November 4, 2010 I think i'm going to make myself a hop unit. I'll keep you guys posted on this one. Quote Link to post Share on other sites
weekenny Posted November 5, 2010 Report Share Posted November 5, 2010 So I removed the grub screw from the flash hider, but when I try to unscrew the flash hider counter clockwise, all I managed to do was strip the threads. It's still firmly attached somehow. Can anyone think of a solution? (I hope I'm not screwed.) Â without the grub screw the flash hider should just pull off Quote Link to post Share on other sites
GismoBE Posted November 8, 2010 Report Share Posted November 8, 2010 I skirmished it yesterday, CQB. Even though the hop isn't good enough (weak range) I had a shizzleload of fun with it! Â Does anyone know anything about the RA-Tech rubber? Does it improve the range? Quote Link to post Share on other sites
PapayaSalad Posted November 8, 2010 Report Share Posted November 8, 2010 (edited) My buddy skirmished with the plastic upper on his KJW yesterday for about 5-6 hours. Absolutely no problems. No noticeable scratches on the inside.  Pictures of the Upper  Sorry about the quality. If you have any questions, just ask. I'd recommend getting one if you want to replace a broken metal upper. Edited November 8, 2010 by PapayaSalad Quote Link to post Share on other sites
arangar Posted November 8, 2010 Report Share Posted November 8, 2010 I just mine less then three weeks ago, ran it a few times and then installed the cradle parts and after a day of minor skirmishing I noticed that my piston cup is cracked and missing pieces I noticed that the rubber on the end of the original piece was pretty chewed up from relatively minor use when I changed to using the cradle parts so it makes me wonder if I got a slightly fudged bolt carrier group. Is there any issue with running the piston cup with chunks missing out of it? It doesn't seem to be cracking anymore now that I cleaned up the mess. Where do I email to get replacement parts? Â Other then this issue I've been loving the gun. I wanted something that functioned exactly like my AR15 and this has fit the bill other then reliablity issues Quote Link to post Share on other sites
t_hum Posted November 8, 2010 Report Share Posted November 8, 2010 You should be able to run it with the cracks no problem. The cracking is quite common, actually. The piston cups are thin and fragile on the end. Any overextension of the piston cup causes that cracking. Quote Link to post Share on other sites
arangar Posted November 9, 2010 Report Share Posted November 9, 2010 (edited) Thanks t_hum... after you told me it wouldn't be an issue I decided to run it in some skirmishing last night and it ran fine and when I got home the piston cup didn't seen to have any further damage. I'm impressed. I also had it chronoed at about 445 without any o-rings on the velocity regulator so it seems to shoot as expected even with the damage. Â I have noticed that my hop up doesn't seem to function the best (which I now see is common enough) but I'm going to have the tech guy on my squad check it out and tinker with it. Â All in all I love this gun so far, I'm glad the piston cup cracking isn't a deal breaker like I thought it was going to be. Edited November 9, 2010 by arangar Quote Link to post Share on other sites
alex chang Posted November 9, 2010 Report Share Posted November 9, 2010 (edited) I just installed my ubr and it it was fairly simple to do. I'll write a short mini guide. I'm not sure if this was the aeg or gbbr as i purchased it used online.  For those in the US, its going to be hard finding a 5mm drill bit and tapping bit, So i just upped the dimensions of the end screw. You have to remove the plate that is between the lower receiver and the buffer tube. Its part 51    The screw on the left is the original screw that came with the UBR, screw on the right is a 1/4 inch x 1 inch long with 20 threads in an inch. You can see i matched the head type so that it fits perfectly with the end cap of the ubr  Remove the lower receiver so you don't mess anything else up and take out the buffer spring and buffer. Clean the brass buffer tube and build it up with some duct tape or electrical tape.  Put the ubr buffer tube back over the brass and drill a small pilot hole so you know where to start drilling. MAKE SURE IT IS LEVEL! Remember you aren't drilling the entire thing through the end cap, you are just using this as a guide. You will notice that the actual hole is not in the middle of the kjw original buffer tube cap. The ubr end cap sits a little higher than the original kjw one.  After about 2-3 seconds of drilling remove the ubr buffer tube and let the fun begin. Drilling into metal is not hard. It just takes some thick oil, a cup of water, and a steady finger. Put some oil on the cap and start drilling. The trick is to go slow and be patient, the oil will lube and prevent the bit from getting too hot. Every 20 seconds or so i would clean the bit off, dip it in water to cool it off, and reapply a drop of oil. The whole process took me about 15 min. I went slow making sure there was enough lube and that i wouldn't ruin my bit. Don't put too much pressure, as the bit will do the work, but also don't just let the bit spin freely.  After the hole is done, clean it out thoroughly and let the tapping begin. This was my first time tapping a hole and it was easy as pie. Some spots were hard so i had to clamp the original kjw buffer cap down so i could turn the tapping tool. Once again make sure everything is level.  After that clean the cap once again, put it back on the original kjw buffer tube. Slide on the ubr buffer tube, screw it into place. TADA! you have a ubr stock on your kjw. No wobbles  Finished product  Edited November 9, 2010 by alex chang 1 Quote Link to post Share on other sites
DesertFox Posted November 9, 2010 Report Share Posted November 9, 2010 Great write up alex, that's exactly how me and my friend installed our ubr. There was a write up in the earlier threads, but it's not quite as clear and certain parts didn't make sense. Quote Link to post Share on other sites
Shadow_Ocelot Posted November 10, 2010 Report Share Posted November 10, 2010 My buddy skirmished with the plastic upper on his KJW yesterday for about 5-6 hours. Absolutely no problems. No noticeable scratches on the inside.  Pictures of the Upper  Sorry about the quality. If you have any questions, just ask. I'd recommend getting one if you want to replace a broken metal upper.   How much did that upper cost him? Did he just buy the upper, or the full upper (i.e. doo-dads like dust cover and forward assist)?   Quote Link to post Share on other sites
PapayaSalad Posted November 11, 2010 Report Share Posted November 11, 2010 How much did that upper cost him? Did he just buy the upper, or the full upper (i.e. doo-dads like dust cover and forward assist)? Â Â Â $25 shipped for the upper. I helped him switch the dust cover, forward assist, hop up, and feeding ramp over to the plastic from the busted up metal one. Took about 15 minutes (exploded drawings helps). I'll keep updating with more use. Quote Link to post Share on other sites
Kai_Wolf Posted November 11, 2010 Report Share Posted November 11, 2010 Awsome! Ty for the pics of the plastic receiver. Question though, how stable will heavy optics and such be on the top rail if it is plastic. Does it feel like it will hold up? Quote Link to post Share on other sites
PapayaSalad Posted November 11, 2010 Report Share Posted November 11, 2010 Awsome! Ty for the pics of the plastic receiver. Question though, how stable will heavy optics and such be on the top rail if it is plastic. Does it feel like it will hold up? Â It'll hold up with no worries. Quote Link to post Share on other sites
Roman! Posted November 11, 2010 Report Share Posted November 11, 2010 So for right now the plastic upper can solve the problems of the cracking tabs on the upper receiver. A solution on mags is coming. Now if we just had a solution for the hop up issues. Regardless, this platform is becoming the standard for out of the box GBB rifle performance and reliability. Quote Link to post Share on other sites
PapayaSalad Posted November 11, 2010 Report Share Posted November 11, 2010 Anyone else try swapping hop up rubbers to fix their hop issues? After changing hop rubbers, I noticed that I was getting much more consistency with my hop up. No more droppers and I can easily overhop .25s on the 4th and 5th setting. This hop up mystery keeps getting more and more frustrating...but hey, this is what fixed mine. Quote Link to post Share on other sites
Roman! Posted November 11, 2010 Report Share Posted November 11, 2010 Will a standard AEG hop up rubber work? Also, has anyone experimented with installing a nubbin piece yet? Maybe a custom made one? Quote Link to post Share on other sites
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