WE M16 Open Bolt Issues

[SF_Chewy]

For the REAPS, look for VSR-10 style as they are the same. I have a few and can attest they are fantastic. They're in stock overseas if you're willing to buy overseas (eHobby).

I believe you can try to shim one side more than the other to help it engage better. Left side higher IIRC. Not sure, Kullwarrior may be able to chime in as I saw his video on this.

For the cracking nozzle, when you manually retract your nozzle does it stick into the hop up rubber abit? I've read that if it doesn't retract quick enough with the bolt carrier it could cause cracking. Try sanding the tip of your nozzle a bit to prevent it from sticking in too far.

With regards to bbdragon, CWI parts. It's labeled as AW on their site
Fire Control Group: http://www.bbdragon.com.tw/product_i...oducts_id/1885

[m102404]

The A+ rubbers are great. The stock rubbers swell and bulge and will hang things up once they're out of shape.

I'm not sure of what part is cracking. If it's the front fake lugs of the nozzle then as said...they're mostly cosmetic. They usually break if there's a misfed BB or foreign object in there when the bolt slams home.

The nozzle doesn't have to retract...but it's not helping anything if it isn't. The fit of the rear of the nozzle in the "cylinder" part of the bolt should be as smooth and frictionless as possible...then use a light coat of grease for airseal. Light sand (i.e. green 3m or 1200 grit), clean, polish as needed. Try different o-rings to get the best fit. A proper fit will result in better gas efficiency especially since a lot of the gas is used to push the bolt back, especially so with heavier bolts.

If you've got a bolt buffer block in the stock tube that may stop it from locking back as well. They're good for taking up shock and making for a snappier cycling of things...but it may be interfering.

The bolt catches on the front left (nozzle facing away from you) corner of the bolt and the rear edge of the bolt catch. The leg of the bolt catch takes quite a beating and so does that corner of the bolt. If they're rounded then just square them off...the exact forward/back dimensions aren't critical. Some bolts have a harder piece fixed there.

If you pull your bolt back with an empty mag it should catch. If it doesn't press on the bottom half of the bolt catch and if it does work then the spring under the catch isn't strong enough to keep it in position. If it still doesn't catch then it may not be long enough (the OB type are shorter and for some bolts you need to file it down so the bolt doesn't hang up riding on it). You can also mod each mag a bit so the notch that sticks up to press on the bolt catch rides a bit higher...but I haven't had to do that much.

To help ease the possibility of the nozzles breaking in the cutouts of the chamber you can chamfer the edges of the chamber areas and the lugs. Taper them a bit so that they slip into position. Dry-fit the nozzel in the chamber to see how much play there is...some are really tight, others are loose. A slightly looser fit is better. You can also shave down the front to back edge of them a touch...the bolt assembly doesn't actually index on the forward edge of the nozzle.

If you've got an empty mag in (dry fire lock on) and the upper/lower closed up the bolt and nozzle should ride back and forth really easily. Aside from just a bit of a hang up on the hammer it should slide nicely. If it's binding tight in spots, drop the mag and try again. If it's nicer without the mag then you can adjust your mag release (try multiple mags first).

If it fires/locks back/runs smooth dry-firing it...but breaks/hangs up/doesn't lock back with BB's...then I'd look at the fit of the mags.

Re. NPAS....with the M4 and longer barrel lengths to get them reliably sub 400fps w/0.20's you're mostly choking off the system. To get them sub 350 the system is barely functional. These things really like to run wide open...downside are high FPS.

With all the WE M4's I've had work well...I haven't done much more than replace the hopup rubber (and in the old ones replace part#66). I've reverted a lot of "fixed up" guns though. Usually not worth the headaches.

[Rotting]

Don't even know what a bolt buffer block is, so I can't imagine that I have one installed (purchased brand new, doubt it was pre-installed).

The old bolt catch I had was pretty worn down, so a steel replacement was put in. Was set up with shims. Thicker on the left, thinner on the right, not enough to compromise the action of it though.

With an empty mag in, the bolt doesn't catch (checked to ensure it wasn't in dry-fire mode), goes back to the forward position. If I press on the bottom half of the bolt catch, it will catch again. You said the spring isn't strong enough, but I don't know where to get a replacement bolt catch spring that would be stronger.

Looking at the bolt carrier, the area where the catch engages looks really worn/rounded. Not sure if this is anything that can be fixed or not.

[Danke]

Check the switch in the mag. The follower trips it and pushes a tab into the catch.

[Rotting]

Checked the switches on the mags. Did dry firing, then popped it open to see if anything happened. No accidental trips from the dry-fire switch. Even when I go to switch it, it's pretty stiff and requires a bit of effort.

[m102404]

A bolt buffer is a plastic or rubber block put in behind the spring at the end of the buffer tube. Pop out the buffer and spring...shine a light down the stock tube. Sometimes they're black...sometimes they're white. It's quite probable you don't have one. But not an issue anyway as you've described.

Check that the mag has the dry fire off...the nub should stick up from the mag. It pushes the arm of the bolt catch to put it into the "catch" position.

Take a file and square off the edge of the bolt that's all rounded off. It needs to be square or else the bolt will ride up and push the catch out of position.

Forget the bolt catch spring strength for the issue you're having.

If you hold the empty mag up and pull the bolt back...does the bolt catch? If so then basically the nub on the mag isn't pushing the bolt catch arm up high enough. It usually happens if there's too much slop/play in the upper and lower receivers.

A couple of fixes for that.
1. Adjust the magazine catch to raise the mag up a bit higher
2. Adjust the bolt catch arm to lower the leg part that is pushed up by the nub on the mag
3. Adjust the mag so that the nub is positioned higher when the mag is emptied

Each of those require disassembly, bending some parts and/or filing some areas.

[Rotting]

With an empty mag inserted (not in dry-fire mode, nub is sticking up), the bolt does not catch. I squared off the bolt carrier where the bolt catch meets, but again, nothing was achieved.

Only way it engages is if I'm pushing on the bottom half of the bolt catch.

[MaybeStopCalling]

Does it engage if you push the magazine up from the bottom?

[Rotting]

Originally Posted by MaybeStopCalling

Does it engage if you push the magazine up from the bottom?

Nope. The mag was checked again to ensure it was not in dry-fire mode. Had the rifle across my lap with the mag on my leg. Pushed down on the rifle to create as much upward force into the magwell as possible. When pulling back the charging handle, it still does not lock back.

[MaybeStopCalling]

Well, I'm stumped.

[Rotting]

Still having this issue. Figured I'd bump this and perhaps someone else would have some input.

[MaybeStopCalling]

Originally Posted by Rotting

Still having this issue. Figured I'd bump this and perhaps someone else would have some input.

The only thing I can think of is your chamber is not quite aligned properly, either a manufacturing defect or just simple installation error has the chamber rotated off of where it should be, meaning your bolt lugs are impacting the chamber or at least making more contact than they should be.

The other thing is that if it's not the chamber, the guides for your bolt are worn or tolerance incorrectly- That would put your bolt off alignment.

The last thing I can think of is it's not an alignment issue. Over about 12k rounds I have broken exactly two nozzles. The first was by snapping to Tap-Rack-Bang during a game and making a double feed worse, and the second was by trying to chamber a round slowly, causing it to get caught between the bolt and the lug recesses, cracking the nozzle at that area. I'd say investigate if anything is causing the bolt to slow going forward, or if anything is causing the bbs to not go smoothly into the chamber.

On the empty lockback, I replaced the standard spring with a Bic Mechanical spring that was cut to have 3/4 of one spring coil exposed from the hole it's inserted in. That generally allows the bolt to lock back but has enough pressure to prevent it from falling aside during firing and giving you false locks.

On the NPAS front... that's confusing. Makes me think that in addition to your cracking bolt issue, the issues you're facing are isolated to that bolt carrier group, or to the mesh of said BCG to the chamber.

[Rotting]

The other things seem to be working fine now after taking advice regarding the nozzles breaking and not properly retracting.

As far as the bolt catch, the last thing I haven't done is the dummy bolt trick. Reason why, is I have no clue how to do it nor what it entirely means to be honest. I don't suppose you have any insight with regards to that method besides the gasguns.info post? :/

[MaybeStopCalling]

To fix the bolt catch on my rifle, I used a cut down BIC mechanical pencil spring with 1/4 to 1/2 a coil protruding from the hole, plus an AEG shim to remove play. On the bolt catch itself I sanded down the L-shaped protrusion to increase the throw of the lever. It now catches 100% of the time, versus the "It works 60% of the time, everytime" status of the older catch setup.

[MaybeStopCalling]

Fair enough. How's that bolt carrier I sent you a couple of months back?