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

[m102404]

This thread is not meant to replace other reference sources. It is meant to distill down the masses of information available from ASC members and choice info from other sources.

As with any forum material...common reference sources very quickly get watered down with repeat questions, half-ass guesses and lack of follow up detail.

So, in an effort to avoid that (and this might fail) it'd be a good opportunity to brain dump definitive personal experiences with mods, tweaks, issues/fixes regarding the WETTI AWSS SCAR, WETTI AWSS M4, WETTI 416.

Please don't post one liners...guesses...heresay...price/customer sales/delivery issues (this is a tech discussion, not a sales/market bitch thread). This is not a discussion of whether GBBRs are viable, nor is it a comparision thread between makes/brands/models.

Please do post info re. fit, function, break/fix issues. Specs, adjustments, practical observations. Links (helpful titles are...helpful) to other good resources.

As you post...I'll strip out the info and merge it into the first couple of posts in this thread. Most likely, I'll not note who said what in the compilation. It's not that I don't think recognition of source isn't important, but more so that I'm not a very good editor..so if gaining credit/fame/cudos is a must have for you to post, don't. If I ask that you delete your post...it'll be for content/editing reasons, please don't take personal offense.

Thanks,

Tys

[m102404]

**need help here guys**
Please post links to other sources (specific to a thread) and I'll gather them here. An informative title instead of just the URL link goes a long way!!
*******************

Arnies
* Arnie's Airsoft UK Forum's Massive GBBR M4 thread (lots of good stuff, but tons of junk too)

Gas Guns Forum
WE-Tech / AWSS (AFC Patented) system (WETTI Thread. WE rep frequently responds and announces new stuff.)

WE Wiki Site (good source of distilled info...specific to WETTI. Manuals, Part #s, etc...)


Other ASC Threads
Kevorkian's WE AWSS SCAR thread

Sim123456's WE M16A3/Nato Steel barrel review

Other

[m102404]

Nozzle/FPS Adjustments
One of the most notable points of the AWSS M4 is that it shoots really hot right out of the box. Velocities (which should be measured with 0.20g BBs and a decent chronograph) typically exceed 500fps with Green Gas (propane). For many fields and venues around here and elsewhere, that is too hot. There's been lots of info already posted on ways to reduce the FPS. Note: The WE SCAR seems to consistently shoot either just a hair over or a hair under 400fps right out of the box...so many write ups are M4 specific and may not have the same affect in the SCAR.
Note: Some of the half-clear M4's were coming in right close to 400fps too..some weren't.
Conclusion: DO NOT go by what it should/might shoot...chrony it to be sure before/during every game.

In general, most methods of adjusting FPS have been focused on positioning the floating valve further forward, which will limit the amount of gas directed down the barrel. Here are some summaries of the different ways (note, these might not be the only ways...if you find others, post up)

Add a spacer behind the floating valve or modify float valve- On WE's forum (***edit link***) they have some pictures of how they insert a solid metal bushing (I think that it's a standard 6mm CA bushing) inside the nozzle assembly. On Arnie's forum guys reference shaving down a common craft bead and slipping it into the nozzle assembly (i.e. not taking it apart)...measurements of the length of the bead vary around 2.4mm (I think...need to check). From anecdotal notes, others have found a compatible nut and tried to thread it onto the rod that protrudes into the nozzle (didn't hold).

Some guys with OCD and too much time on their hands...have gone so far as to machine small brass cylinders that fit inside the nozzle assembly, threaded to fit the end of the rod. Varying sucess with lengths of 2.4-2.74mm.

The same dummy has gone even further and machined a series of brass replacement floating valves...with different bore and hole diameters. I'm (oops, I mean HE) isn't finished testing at the time of this writing. They work and will get the velocity down to 400fps consistently...but not 350fps (which is a common indoor FPS limit).

***EDIT Sept 19, 2009***
Due to a happy mistake, I received a new nozzle and brass chamber for my M4 AWSS. Unlike my stock gun, this nozzle was shaped just like the SCAR AWSS nozzle in that it was stepped and wider at the body. It was mounted on a long (regular) M4 rod and piston unit though...odd. The short SCAR length rod was included in a baggie...so I wonder if it comes that way or if they mix and match at the factory. Anyways...although disappointed at first, I tore into my M4 and compared the parts. The cross pins and external cuts/dimensions matched between the "SCAR" unit and the "M4" unit. Yeah! As long as you use the "SCAR" nozzle with the "SCAR" brass chamber/tube (and similar for similar in the case of the M4 parts)...you're good to go...straight drop-in swap. I had cut my inner barrel to CQBR length and with the stock "SCAR" nozzle...FPS was bang on 400fps w/ 0.20g BBs.

Shameless rip-off of Kevorkian's SCAR Nozzle Pic

Originally Posted by m102404

It's a WETTI part. I got my camera sorted out...I'll try to take some comparison pictures and post them. (NOTE...figured out the previous firing issue...edited my last post with notes)

So...theoretically, the RA-Tech WETTI NPAS Adjustable SCAR nozzle should "drop" right in, if you have the matching chamber to go with it.
Pic#1/#2 - Top to bottom
- Stock WE AWSS M4 Nozzle (note it has one of my custom valves in it)
- Stock WE AWSS SCAR Nozzle (mounted in M4 bolt
- misc handmade valves (different ports and bore hole sizes...brass)
- bottom left in Pic#1...threaded spacer to fit on rod behind float valve
- center - stock float valve with threaded screw for adjustment



Pic#3 - SCAR nozzle fit (doesn't fit all the way in) into stock M4 Chamber, notice nozzle setback


Pic#4 - stock M4 AWSS nozzle fit into stock M4 chamber, seated fully. If you look really closely at the top nozzle...through the inlet hole, you'll see a bit of a handmade float valve.

If, after a lot of shots and taking your piston/bolt assembly apart several times, you notice that semi and full auto are behaving erratic...check that the UHMW spacer that sits on the body of the piston (to keep it centered in the bolt) hasn't nudged itself up towards the front of the bolt. Mine was repeatedly moving up, sort of centering itself on the two holes of the piston body...moving it back fixed it all up. I replaced it with a new spacer (that isn't loose at all) and things work just fine now. It's probably because I've disassembled mine over a dozen times that it's loosened up...as new, it's a quite a tight press fit.

Main Rifle Functional Issues/Fixes
Kevorkian's SCAR Bolt/Hinge Plate Pics and Thoughts

Magazine Functional Issues/Fixes
Manchovie's General Comments

Accuracy/Feeding/BB Weights

EDIT May 3, 2010

Nozzle
* all current gen M4's have the new style nozzle, the same as the one released with the SCAR. It is sometimes refered to as the "CO2" nozzle. You can shoot duster, propane and CO2 through it.

Version Info (great summary from Spartan117)
http://www.airsoftcanada.com/showthread.php?t=102339
"--------------------------------------------------------------------------------

There are many people out there that have wondered about the WE system and its different generation models. These go from Gen 1-4. I will briefly explain the difference between each generation. **Note This information is based solely on what I have gathered about the WE system**


GEN 1 (m4 only)

- Nozzle is made out of brass and has only 1 O-ring seal.
- The hammer has no roller ball bearing for the Bolt carrier group (BCG) to ride smoothly
- A generation 1 m4 has no markings


GEN 2 (m4 only)

- Uses the same brass nozzle and single O ring
- The hammer now has an added ball bearing to allow the BCG to move back and forth smoothly
- A generation 2 WE m4 has laser engravings
- Body of the gun, I believe is an anodized finish like the rest of the generations from 2-4


GEN 3 (m4, hk416, scar)

- The nozzle is now made of stainless steel and now has a double O ring for better seal
- Has the same ball bearing on the hammer
- Engraved and anodized body
- SCAR has a reinforced hinge plate to prevent breakage.


GEN 4 (AKA CO2 system: M4, hk416, SCAR)

- The nozzle again is made of stainless steel, double O rings for better seal, and is now reinforced with a bearing or plate to help the bolt withstand the force of propane, green gas, and CO2.
- ball bearing on hammer
- body is anodized and engraved


One last thing to mention.....other than the different generations there are also the WETTI AWSS models which are meant for military and LE training. Not sure what the different is, but according to what James, from WE, has said, the WETTI version has reinforced parts. "

[m102404]

TSC M4 Nozzle for WETTI AWSS M4

RA Tech WE SCAR Nozzle

New Hopup Rubber (Black)

6.025mm Chrome Tightbore

Fit/Function External Modifications

[m102404]

C3SK's Field Report from RAWDON

SniperChic's Field Report

[Hata]

damn, my charging handle on v3 m4 just broke after I run 1 mag w/ green gas... (green gas killing it)?
Any suggestion on more durable charging handle?

[Karma_]

Get a steel one. All the WE ones break.

[Nabisco_Lobstrosity]

How To Replace Your "Firing Pin Stop" In Your WE SCAR-L:

If you're running CO2, get the new "firing pin stop". It looks like this. I am in no way endorsing Evike. I am simply providing an example of the part in question. My understanding is that this stock part has a high failure rate. If you don't feel it's important, then don't get it. It's 10 bucks (US), and if you don't mind a small amount of technical work it's easy to replace.

For WE M4 users, it is listed as "Part #066" in your manual. For WE SCAR-L users, it isn't even listed in your manual. I can't speak for the WE M4 users, as I only have a WE SCAR-L, but I can give a rundown of what you will need to do in order to install this part. It is not as daunting as some people might think.

1. Remove your Lower Receiver - pop the pin out, slide the lower receiver forward, then remove it.
2. Locate your Fire Selector switches, and remove them - turn it to 'A', and continue turning it until it is pointing at the 7 o-clock position; locate the small hex screws on both levers; PAY ATTENTION - there is a small steel bearing, sandwiched between the lever and the receiver, held in place by a spring.
3. Remove the steel part of the Fire Selector that the levers were attached to - I find it helps to rotate it while pushing it towards the right side of the receiver. PAY ATTENTION - to its orientation before you remove it. Note the positions of the 'grooves' that let the Fire Selector do its job.
4. Locate the small flat-head screw, found above the Magazine Release button on the right side of the receiver. Unscrew it.
5. Locate the small star-head screw, found inside the receiver, directly above where the grip would be - Unscrew it; you should see (looking down from above, towards the bottom) a second star-head screw near the front of the receiver - you do not need to remove it.
6. Lift the Trigger Assembly out of the Lower Receiver - it helps to push from the trigger on one side, and left from the top. PAY ATTENTION - there is a small, rectangular piece of steel that has a very small 90-degree bend to it (it would look like a capital 'L' from the side); this is on the right side of the Trigger Assembly, but if you rotate the entire object, it may fall out of its position.
7. Locate the part to be replaced. PAY ATTENTION - there is a small spring pushing down on it.

So there you go. You can replace a very important part of your GBB, and you didn't even need to get into the really fun stuff inside the Trigger Assembly.

[Hata]

RA-TECH NPAS for WE M4 is out!!

[Sim123456]

Just to say that in the M16A3, inner barrel lenght is 509mm, as shown in my review.

[m102404]

Originally Posted by Hata

damn, my charging handle on v3 m4 just broke after I run 1 mag w/ green gas... (green gas killing it)?
Any suggestion on more durable charging handle?

There are steel replacement "airsoft" ones...or I've read that you can use a real-steel one. The only difference that guys have pointed out is a little bump/nub on the airsoft one...and at least one guy took a real one, drilled and tapped a hole and used a grub screw to create the bump that is needed. Gun Gas Info forum has pics of that.

Do you recall how/why it broke? Was it while you were racking back the charging handle? When you let it snap forward? Was it not all the way forward when you fired the first shot?

[m102404]

An update ago I noted that I had received the "new" "WE M4 CO2 upgrade nozzle" instead of the older slim version that I had received with my M4. The new one looks just like the scar nozzle (longer rod though) and just like Hata's pics of the RA Tech NPAS (minus the adjustment bit).

I swapped in the new chamber that matches the nozzle profile and things seemed to work just great.

However....my nozzle is toast. I'm not 100% sure how, but the thin section by the inlet cutouts have collasped and the nozzle is toast. I suspect that it was more from a jam, where then the nozzle/bolt came smashing into it and the thin stand-offs of the nozzle couldn't take the strain. I kind of wonder if the overall length was too long....but unfortunately I didn't take any measurements of it to compare against my original setup....I kind of doubt that though, they seemed to be a nice fit.

If you look at Hata's pics, you'll note that the plastic tube spacer is missing from the assembly (probably since for the upgrade kit you need to use your stock one from the original assembly). You can see the opaque spacer in my pics back in one of the first posts of this thread.

I think that the length of that spacer is quite critical. It ensures that the nozzle is kept far enough forward so that the nozzle is firmly sealed/seated into the chamber. Obviously if the nozzle was allowed to sit back when the rifle fired, a lot of gas pressure would be lost.

In the event of a jam...the metal nozzle is forced forward by the bolt spring and has the weight/heft of the bolt assembly riding with it. That's enough to smash/crush bbs...and I suspect that if there's no give in the particular jam, the nozzle could suffer damage (as mine did).

So if the objective is to keep the nozzle pressed firmly forward...yet have some give in the event of a jam so the nozzle isn't damaged...then it might be an idea to replace the solid plastic spacer with firm but yeilding rubber.

I might try a bit of rubber tubing, rubber washers, or even a disk of sorbo type material on the next nozzle that I get.

[Hata]

Originally Posted by m102404

There are steel replacement "airsoft" ones...or I've read that you can use a real-steel one. The only difference that guys have pointed out is a little bump/nub on the airsoft one...and at least one guy took a real one, drilled and tapped a hole and used a grub screw to create the bump that is needed. Gun Gas Info forum has pics of that.

Do you recall how/why it broke? Was it while you were racking back the charging handle? When you let it snap forward? Was it not all the way forward when you fired the first shot?

I am shooting in semi at the time it broke and the very last shot, I feel like a spring broken inside the top receiver. The next thing I know is the gun is jam and I can't even pull the trigger.
Attempt to open up, but I can't since the bolt carrier is a little bit backward and I have to remove the upper completely before I can remove the bolt carrier. The Little piece broken off is suck between the bolt carrier and the hop-up, so I have to remove the front set in order to take out the broken piece.

[Karma_]

Mine broke when I pulled it back. I purchased a steel one from Airsoftbuddy which didn't fit. It slid into place but the back was too thick to go in all the way. I filed the opening for a couple minutes and now it's good to go.

I also got in an order of mags. All six were fine, no leaks, but one of them broke right at the loader. A piece broke off so now I need to replace that part. Not a big deal, it's only $5.

I'll be ordering the NPAS for it today so we'll see how it does. My gun is shooting a steady avg of 498fps right now.

[Hata]

Originally Posted by Karma_

Mine broke when I pulled it back. I purchased a steel one from Airsoftbuddy which didn't fit. It slid into place but the back was too thick to go in all the way. I filed the opening for a couple minutes and now it's good to go.

I also got in an order of mags. All six were fine, no leaks, but one of them broke right at the loader. A piece broke off so now I need to replace that part. Not a big deal, it's only $5.

I'll be ordering the NPAS for it today so we'll see how it does. My gun is shooting a steady avg of 498fps right now.

Which one did you buy from airsoftbuddy?

which NPAS you ordering? the one for M4 or SCAR? I can't find anywhere selling the one for M4. I msg RA-Tech from GGI but no reply yet.