WETTI/AWSS - M4/SCAR/HK416 - Technical Summary Thread

[Fuzzy]

Originally Posted by turok_t

Ive tried and owned both the open and closed both system for the WE M4. When the gun fires, sometimes gas is discharged from the ejection port. This reduces the gas efficiency and I hate to waste gas, especially when more is needed to cycle a steel bolt. Any remedies for this issue?

Isn't it part of the design?

The valve in the bolt directs some of the gas out the front of the bolt to fire the bb. The remaining gas gets directed out the back of the bolt and into the bolt carrier - and eventually out the ejection port.

Based on this, gas will always be discharged from the ejection port. Whether you see it or not will depend on temp, humidity, amount of oil in your mag.

[Ballcancer]

Anyone had any problems with the bot lock after converting to open bolt? Once I converted, the bolt lock stopped working for all my mags.. I found that the bolt lol function on the mags are not pushing the bolt stop up far enough ... I put some epoxy on there, and it did the trick right away, but that got blown off after around 50 rounds. I compared the open bolt bolt stop to the closed bolt on and I noticed that the portion that is pushed up by the mag stop function is thinner than on the closed bolt one. Anyone have a similar issue? I'll try the epoxy again maybe I need to rough up the contact surface a bit more and let the epoxy dry longer...

[Eeyore]

You need to shim your bolt catch. There is too much wiggle left to right in it.

[Fuzzy]

The bolt catch is a common problem. You can try the TSC bolt catch plates.

[turok_t]

Originally Posted by Fuzzy

The bolt catch is a common problem. You can try the TSC bolt catch plates.

I tried using the TSC plates, its not going to work, what you need to do is shorten the bolt catch spring because the magazine plate has to overcome the force of that spring in order to engage the bolt catch... Also, you need to file down the horizontal section of the "L" on the bolt catch like the one for the closed bolt system. Removing this section maximizes the contact area between the bolt stop and bolt as shown below. My bolt catch has been working flawlessly after some modifications. If you want, you can also add spacers or washers in the buffer tube to short stroke the gun so that the bolt catch can catch the bolt immediately/quickier when it begins its return cycle. Also, adding washers/spacers can lessen the impact on the bolt catch.

[Fuzzy]

Good stuff Turok. I'll try your mod and see how it goes.

[neilgoth1974]

Quick question guys, at what part does gas vent at the charging handle? Does it vent more on the top or bottom part? Reason why I ask is I'll be modding the charging handle a bit with a small channel to redirect the gas away. Looking at the wiki site the mod is on the bottom wheras on the real PRI gas buster handle the deeper channel is on top. Thanks in advance for the inputs guys.

P.S.
Any preventive measures on how to get rid of surface rust? It's quite humid here in the Philippines and some parts are already showing signs of surface rust.

[Thenooblord]

the charging handle has nothing to do with gas flow

[neilgoth1974]

^ Thanks Thenooblord, what I meant was the gas that gets blown to your face from the back of the charging handle, from what I've read at the wiki you could make a seal on top using a bead of RTV and make an extra channel below directing that gas away. Then I looked at the real PRI handle and they had that channel on top. Just had extra time to tinker with the gun so that idea ran around my head

[Huron]

I can't for the life of me find a 10.5 inch barrel for the M4... Searched here and on several HK retailers and no luck. Are there no aftermarket barrels for the WE M4's?

[shaharov]

Ok... have a weird problem that has sprung up in my SCAR. it seems that is semi only when the bolt comes back it's jamming on the hammer and the only way to release it is to remove the lower reciever. This doesnt seem to happen in full but I'm pretty sure that that's because the hammer is lower until the bolt reaches the closed position again.

I've filed a litttle bit of the bolt down (specifically the hard lip where the hammer catches). This seems to help a bit but wondering if anyone else has had this happen and if so if they have a fix.

BTW... this is an open bolt system and has worked well for a number of months before this happened.

Shaharov

[shaharov]

Anyone have any ideas?

[Boyso]

I'd like to know if anyone as succeeded to remove the trigger guard without breaking the ears in the process?

[MaybeStopCalling]

Quick question for those in the know: Is it possible to overtorque the barrel nut on the M4? I tightened it as hard as I could (one hand on the upper and one on the armourer's wrench), then I backed it back a notch so the gas tube could fit, but now thinking about the strength of that upper's aluminum is making me a tad uneasy.

I will say that barrel is rock solid now.

[m102404]

short answer is yes. Same with AEGs...but with a GBBR you have the bolt essentially pounding on the chamber/barrel...which would add stress to an already stressed part. There's more than one person who has ended up with cracked receiver threads...either from over tightening, or over tightening and then eventual failure.

If you take a close look at the stock out of the box setup, you'll note that there is an o-ring set on the out barrel and it's captured by the delta ring. That ring is there (IMO) for two reasons...1) to provide a "squish" fit for tightening things down...2) to provide a bit of a bumper to take up shock (this one is a fuzzy guess).

I've run many rounds with the front end built up with 1) oring...2) AEG barrel shims...3) nothing. Currently I run it with an oring in place.