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
Quote:
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.
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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. "