WE M4 receiver won't detach

[Stocko]

Hey guys.

Trying to see what's wrong with my gun. When I tried to take out the rear receiver pin and split the upper from the lower it wouldn't budge.

During a game earlier today I chopped one bb. I managed to get the lodged bb out and it was firing semi perfectly. However full auto 3-5 shots and it would need to be pushed into semi in order for the gun to fire again.

Right now I don't see any obstruction from the ejection port, no bb stuck and the bolt racks back and forth smoothly. I just can't seem to split the receiver. Any suggestions?

[ShelledPants]

This happens from time to time because of an issue with the bolt and it's alignment with the trigger group. If the bolt is marginally to the rear due to a chopped bb being stuck in some obscene place around the nozzle or even above the bolt, the gun will appear to be held together by magic even with both pins popped.

What you have to do is (with some patience):

Rack the gun and set it to semi. Close the bolt. The hammer is now cocked.
Pop both receiver pins, rear first.
(and here's the hard part to conceptualize)
While rocking the bolt back and forth 1mm-2mm, attempt to move the upper receiver directly upwards and forwards.

This motion is NOT the same as pivoting the receiver around the front receiver pin. Just straight up from the lower and forward along the path of the barrel.

If you CANNOT get the receiver to split, attempt the above with the gun in the fired state, with the hammer decocked.

I've had to fix this on a buddies gun a number of times while he was getting his Open Bolt kit worked in on his old as fuck Closed Bolt gun.

If you get the monster apart, check EVERYWHERE on and in the bolt for a chopped BB or loose / broken parts before reassembly. Also check the trigger group visually and the topside of the upper receiver and hop up unit opening. White chips in any of these places will cause the weirdest shit to happen.

[Skeletor]

Shards of broken bb may also be mulched into the fake lugs of the hop up chamber, keeping the bolt from seating fully forward. Take a flash light and look into said area.

If this is the case then I find the easiest way to fix this is to grab a delta ring wrench and remove the front end of the gun. This will also allow the bolt all the way forward so that you can now split the receiver in half properly. You can then easily clean out the hop chamber.

If it is hammer trouble, usually you can still split the receiver a little. Enough to push a thin, flat head screwdriver in to depress the hammer a little more.

[Kos-Mos]

Broken hammer/sear and nozzle can cause the hammer to follow and get wedged in the nozzle opening.

Punch pins, and insert some flat tool (butter knife is my favorite for this job) between the receiver, at the middle of the magwell, and slide it back.
You might have to rack the bolt at the same time, but if that was the issue, you will feel it free up.

[Stocko]

Thank you guys. I will try all these suggestions when I get home. Starting with the butter knife trick - easiest haha. I felt so hopeless and was about to tear it apart.

Quick question: is it possible to buy an armorers wrench and unscrew the stock/buffer tube and slide out the bolt if worse comes to worst?

[Skeletor]

You can unscrew and remove the buffer tube, but you won't be able to remove the bolt. The gas key on the bolt will get caught on the receiver.

If it's really difficult and the other suggestions don't work, just use the wrench to remove the delta ring on the front and pull the whole front end off. That should let the bolt move forward enough in the receiver to split it open.

[Drake]

Another thing you can try that's fairly easy is pop both the front and rear receiver pins out and try to split it open. Sometimes the tiny amount of play removing the front pin will give you is enough for the bolt carrier to clear the back of the lower receiver.

[Stocko]

Thank you guys. It took about an hour to clean out all the debris.

I had to hold the bolt open, and clean the nozzle and where the nozzle makes contact (I found two smashed in deep in the crevices). Then after a very thorough cleaning, I finally got the bolt pushed forward far enough to detach the receivers.

When opened, I also found a bb sliced in 2 buried in the trigger group.

Gave it a good cleaning, ran about 3 mags through it and took out the bolt. aaaannnnnd its good!

[BobbyDangerous]

Yeah, BB's jammed up pushing the bolt carrier back into the buffer tube. It's won't come apart.