WE M4 CQB-R Firing Issue

[BlackBerry]

Hey guys,

Hoping you can help me out with this one. I've looked through the technical thread, but may have missed it.

The problem is that my M4 fires, but no bb's come out sometimes it does, sometimes it doesn't. I am assuming its a jamming issue.

So heres what I've done. I took it apart, cleaned and re-lubed everything as per Mr. ShelledPants M4 Cleaning Guide (great guide btw). I've tried adjusting and playing with the hop-up to no avail. I've thoroughly checked inside to make sure there are no chopped/crushed bb's. I've also cleaned the barrel inside with a long swap in case of dust build up or dirt. I thought maybe my mags were a problem, so I crossed checked it with 4 other working mags, but the problem is still existent.

Not quite sure what else I can do other than find a local gun doc to have a look at it. Any suggestions would be appreciated.

Some more details:
-WE M4 CQB-R (Version 3 I believe)
-Using .25 BB Bastards
-NPAS installed set to shoot at around 350 fps

[J-Man19]

Are you using a hicap or low/mid mags?
I sometimes have feed issues with my kwa and have to jiggle the mag for bbs to feed properly.
This is me assuming it's and aeg and not a gbb, just skimmed your post.

[BlackBerry]

It's a gbbr

[Ross]

When you fire the gun and it jams. Where do the bbs jam? Do they stack inside the barrel?

[Blackthorne]

Quite often with NEW WE M4s there is way to much hop applied, even with the hop all the way off.

When you tear it down, look to see if there are small plastic shims between the nubin and the hop-up rubber. If there are take them out (if more than one, take out one) and see if there is a difference.

Play around with it until it works consistently.

[m102404]

1. Does it cycle (not necessarily shoot a bb, but rather fire and reset) normally for semi/full auto?

2. If you insert a mag with bb's and rack it and fire (in semi)...does the BB shoot? Does it load another BB (guessing not always from what you originally posted)? Check by dropping the mag, rack the bolt and look into the chamber.

3. When you say jamming, do you mean that more than one BB is getting shot out? there are a bunch of BBs jammed into the chamber? Or rather...a BB isn't being loaded into the chamber with every cycle.

4. Are the feed lips of the mag ok? If you use something to flick the BB's out of the mag one by one...does the next BB pop up into position cleanly/properly?

5. Does the stock nozzle/setup work fine? Helps narrow things down.

6. Did you install/change any other parts?

Tests
1. Openup the NPAS to max velocity. Does it cycle/feed/shoot properly? At just under 350fps (depends on temperature) the system is almost choked off...it may be short cycling when the bolt isn't coming back enough to pick up the next BB.

2. Try the stock nozzle body...but keep the RAtech NPAS floating valve and spring. If you have calipers measure the outside diameter of the nozzle tips. I've noticed a batch of RATech nozzles have come out where they're a bit bigger (in diameter) than the stock nozzles. The little difference causes the nozzle tip to wedge into the chamber tightly. This can hang up the firing cycle and cause misfeeds. So far as I can tell....aside from those dimensions there's little difference between the stock nozzle and RATech nozzle (I've been using the stock nozzle body for ages and it's held up well).

[onemenace]

First thing to do is determine where the bb is getting jamed.

Possible problems are if you didnt install the barrel correctly, meaning if the brass tube is not properly aligned into the top receiver the mag feed lips wont properly sit this could be an issue.

Second could be the bb chamber I believe its part #122 it sits just on the tip of the inner barrel its can be frayed or torn or swelled up from too much silicon oil. I'm guessing that this us probably what is causing the jamming issue.

I would dissemble the gun again inspect this piece and determine its condition and then order that piece and possible few backups along with hopups.

Another idea your guide rod could possibly be bent check to make sure everything is snug and nothing is loose on the any part of the bolt guide rod nozzle.

Make sure that the npas is not completely turned off or on so I would try adjust it see if that makes any difference.

Other than that try some of these suggestions post your findings and you might want to check this website.

http://wem4guide.wikidot.com/troubleshooting

There is amazing information on it and has helped me greatly.
on a side note toms guide is very well done but one thing I noticed and a mistake I made myself is really how much lube to use and how to smooth it out. these guns require a minimal amount so just make sure you are not over lubing the gun something I discovered on the guide on that website.

Best of luck!

[BlackBerry]

Hey guys, thanks for the replies. I was away at Blue Mountain so I couldn't reply sooner.


Update:
-I disassembled the gun and did not find any shards nor broken bbs in the hopup
-What I noticed was that the bb does not necessarily jam, but rather it misfires
-When I shoot semi it appeared to be cycling properly, as in it would reset, but 8/30 bb’s would not come out, the second shot(sometimes third) would send both out.
-I thought it was a jamming issue, but when I pointed the barrel downwards I noticed the misfired bb(s) rolled out
-On one misfire incident, I pointed my barrel downwards and shook the rifle a bit, usually the bb’s rolled out, but this time it didn’t
-I proceeded to open up the gun and check the barrel, I found 1 bb stuck just before the retainer
-A majority of the time though the bb would roll out
-To the best of my knowledge, I believe this inconsistency is due to the hop-up or retainer thing that holds the next bb in chamber
-So I tried adjusting the black hop-up all the way CW and fully CCW, but the problem still persists
-I than turned my NPAS all the way up and down, but same problem
-The RATech nozzle seems to be fine, it worked proper in the past, but it was just recently that this issue started
-Prior to this issue I haven’t changed anything internally/externally

Variables Eliminated:
-I’ve used 2 different batches of Bbbastards .25’s and some Mad bulls .25’s (bb’s are not the cause)
-I inspected all my magazines and the lips and they all look proper (I also tested them on my WE Scar with no problems)

My theory is that the hopup is damaged. I’ve already placed an order for a new Stinger hopup, soon as it comes in update. If you guys have any other theories or suggestions, please share!

[m102404]

Just a point of clarification...with the black adjustment ring dialed all the way back (to the rear)...the hopup is off as much as it'll be.

Forward = more hopup

[Ross]

While it's always good to have an extra stinger hop up on hand, I do not think this is your problem. Before I modded all my magazines for my scar, I had problems with chopped bbs. My gun would consistently fire parts of bbs, and not full ones. During this process, my hop up was ripped to shreds. The completely destroyed hop up made my gun's accuracy hilariously bad, but it never jammed my bbs.

Of course I could be wrong. But what sounds like is happening to you is your bbs are stacking inside your gun. I think it may be your npas valve not consistently pushing the bbs all the way into the inner barrel. If you suspect your hop up is damaged, you should take your gun apart and see if it is.

[BlackBerry]

Update:
Alright.. so I got finicky sitting around waiting for the stinger to come in, I decided to check my stock hop-up again..everything looked fine despite my suspicions. I took up Ross's NPAS valve theory and decided to shave off the tip of the nozzle as per the WETTI Technical Thread. Now there is no jam and the gun shoots flawless! I compared the diameters of both the stock and RA-Tech nozzles before sanding and I gotta say they looked VERY identical in size. I guess it was a difference of a millimeter, anyhow thanks for the help guys!

On a side note: I've been hearing a lot of problematic modifications involving RA-Tech products lately. What gives? I really wanted to order a 6.03 barrel, but now I'm hesitant.

[Ross]

Originally Posted by BlackBerry

Update:
Alright.. so I got finicky sitting around waiting for the stinger to come in, I decided to check my stock hop-up again..everything looked fine despite my suspicions. I took up Ross's NPAS valve theory and decided to shave off the tip of the nozzle as per the WETTI Technical Thread. Now there is no jam and the gun shoots flawless! I compared the diameters of both the stock and RA-Tech nozzles before sanding and I gotta say they looked VERY identical in size. I guess it was a difference of a millimeter, anyhow thanks for the help guys!

On a side note: I've been hearing a lot of problematic modifications involving RA-Tech products lately. What gives? I really wanted to order a 6.03 barrel, but now I'm hesitant.

This is great news. RA's precision inner barrels are nice. As soon as I installed it, the bbs would jam when I fired it. I was going to start sanding down the npas but before I could do that, a trigger piece broke. So I'm assuming the gun will work fine as soon as I can get that piece replaced and npas sanded.

Can I ask how long it took to sand down your valve? And was it difficult? Was is a lot of trial and error, or did it work right away?

[posilon]

lube up the mags with oil.

[BlackBerry]

@Ross

I can't recall exactly how long it took me to sand being as I would put in about 1-2 minutes of work during Cod: black ops' intermission LOL. All in all I'd guesstimate roughly 10 minutes using 400grit and gently applying even pressure. I was very paranoid of over sanding it so I'd stop after 1-2 minutes each time to re-clean and put it all back together and test shot a full mag. I did this about 4x before I noticed I could go through 5 mags without any jams. Hope this answers it!

[m102404]

To describe the "sanding down the nozzle" in another way...

Take a pencil in your right hand....eraser end pointed to your left hand.

Take you thumb and pointer finger of your left hand and "pinch" the sides of the eraser.

With your right hand...twist the pencil back and forth like you're sharpening it.

That's about it....but use a 400/600grit piece of emery cloth (wet/dry sandpaper will do) to pinch it.

You are not changing the nozzle tip profile/design/curves/etc...at all. Just reducing the diameter a bit.

I'll have to mic the stock one vs. RATech one again...didn't write down the numbers. It's not much at all really...but it does have a marked difference in action.

Basically you're aiming for the nozzle to almost just not stick at all. When you rack the bolt back (you can do it by hand by just grabbing the bolt carrier)...it will extend out the rod. Up until the end of the extension, the nozzle is still in the chamber. Just past the full extension of the rod, you'll have to give the bolt carrier a tug to free the nozzle from the chamber. If it's "stuck" then you're going to have inconsistent/wonky action. Basically there should just be the slightest amount of pull needed to free it. You want it to create a good seal...but not a jam tight fit.

Same again when chambering...the nozzle should go into chamber easily by hand (it will no matter what with a big recoil spring pushing it ). If you feel that you have to press the bolt carrier into place to seat the nozzle fully...it's too tight.