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

[Ross]

I just want those tiny magazines for my scar.

[The Chad]

hahaha as if you made that Gif.

[Ross]

maybe....

[turok_t]

Open bolt video..

http://www.youtube.com/watch?v=zmzI_...embedded#at=11

time to upgrade our guns!

[Ballcancer]

I was plinking with my m4 today and i noticed a slight wobble between my upper and lower recievers... have any of you guys had this before? should I be concerned?

[ShelledPants]

Originally Posted by Ballcancer

I was plinking with my m4 today and i noticed a slight wobble between my upper and lower recievers... have any of you guys had this before? should I be concerned?

Most WE m4's have a little play, it perfectly normal. My gun had TONNES of play, (comically so at one point...) and still fired flawlessly.

[Ballcancer]

Ok perfect... Thanks a lot SHelledpants... I guess its just more of an annoyance lol.. apprecaite it!

[m102404]

Mine has a bit of wiggle too...and I think with the materials that it's made of, and the stresses that it's under, a bit of slop is preferable to a tightly fitted but stressed out part.

[Ballcancer]

Yes that makes a lot of sense actually.... Now would the receivers become more wobbly over time due to the stress (which would be expected) or would it stay the way it is now? I just need to know if I have to put a separate set of funds aside for a new receiver set. Thanks for your reply guys!

[Brian McIlmoyle]

Originally Posted by Ballcancer

Yes that makes a lot of sense actually.... Now would the receivers become more wobbly over time due to the stress (which would be expected) or would it stay the way it is now? I just need to know if I have to put a separate set of funds aside for a new receiver set. Thanks for your reply guys!

if it's not cracked .. and everything works don't worry , a couple of mine are a little wiggly too

[pugs144]

Most, if not all AR rifles have some play between the upper and lower. There's nothing to gain from removing that play. Products like the Accu-wedge do nothing but make it a bitch to break down your rifle.

[Ballcancer]

Yea I didn't think it would be much of a problem, I just wanted to make sure that it was normal. I appreciate the answers thanks!

[The Chad]

Anyone know what a reasonable price for a used Black SCAR with NPAS should be?

[m102404]

I didn't see this specifically written up elsewhere....so I'll dump some notes here and repost it in other spots if needed.

I picked up a WE PDW (short barrel, black) the other night and spent some time tearing it down and giving it a good once over. Any loctite mentioned is blue/temp type....any lube/grease mentioned is either "Superlube" (clear gel PTFE) or 60wt Silicone Oil.

From Muzzle to Stock

Flashhider
- the outer cage of the stock flashhider captures a black plastic spacer that centers the inner barrel...a nice touch. I loctited it to the main flashhider body so it wouldn't come loose with use.
- the flashhider (of course now I can't recall if it's CCW or CW....I think CCW) is 14mm standard size and is backed with a aluminum collar and a o-ring. I left the o-ring and collar...and added just a touch of loctite to hold the flashhider

Outer barrel Assembly
- the short barrel version is a solid one piece barrel vs. the long barrel version which is a short piece that ends at the "gas block" and then another extension is held to the gas block with a grub screw. On more than a few PDW's I've seen that the gas block grub screws are missing or loose...so loctite them if you've got them.
- on the short barrel, the gas block retains the rearmost grub screw and 2 cross pins. It's also drilled and tapped for the foremost grub screw...although that hole is empty...I might find an extra grub screw and just put it in so dirt doesn't collect there.
- to remove the front barrel assembly from the upper receiver...remove the two large hexhead screws from the bottom of the lower handguard area. The entire barrel assembly will slide out. Note that the two screws are different lengths...and that the holes they came out of are different depths. Note that there are two notches on the assembly where it indexes on lugs in the receiver...it's worth touching that with some grease so it doesn't seize up over time.
- once the front barrel assembly is out...you can remove the two grub screws that hold the "rear gas block" to the outer barrel. There is a short one at the top (12 oclock position) and a longer one at the 6 oclock position. This longer one pins a collar around the chamber/inner barrel/hopup unit. Once that grub screw is out...you can pop that collar out. By moving the rear gas block out of the way you can expose the cross pin that holds the brass tube/chamber to the outer barrel. You'll need a good punch to knock that out. Then you can hold the brass tube and give the area around the collar a couple of taps and the collar should pop out.
- while it's apart...take note of the two collars that hold the "gas rods" into the front gas block. They are cylinders that screw into the gas block...mine were loose, one was actually detached completely. Loctite a bit and screw them in tight.
- the rest of the hopup/inner barrel/chamber assembly comes apart like the other closed bolt systems.
- as with other ones that I've seen...the hopup rubber nub was squashed on one side. Basically whomever is putting them together isn't taking the time to fit the entire hopup nub into the hole in the inner barrel. This will deform the hopup nub...usually resulting in craptastic hopup action. I replaced it with a spare smoke/black rubber I had.
- the inner barrel was FILTHY...it had grease and crud in it. I used at 5.56mm jag and some cotton patches with silicone oil on it to scrub it out. I kept patching until it was clean and shiny again. For that kind of cleaning...take your hopup rubber off...and make sure the hole is clear before putting it back on.
- a little grease in the threads of the hopup adjustment wheel will help as the rifle gets wet/dirty/used
- wipe out the chamber/cylinder with a mop jag
- reassemble the front end/chamber/barrel assembly....make note to seat the cross pins fully and to seat the collar fully. You may need to give it some taps with a punch to seat it flush.

Nozzle/bolt
- the stock WE PDW nozzles (and the SCAR ones for that matter) are crap. The piston body flange will warp/bend with use as the metal is soft-ish whatever. You can tap it back tight...but that's temporary. Steel upgrade for that.
- the stock WE PDW nozzle tip is different from the other closed bolt nozzles...the tip is narrower. Essentially where there's a notch in the other nozzles...the PDW continues that notched diameter right out to the tip of the nozzle.
- RATech NPAS' will fit just fine
- The nozzle head spacer is a metal shim (forgot the thickness) and a 1.68mm plastic "spacer". The issue with cutting that plastic so thin is that it cracks. Mine had 4 cracks forming in it already...I've seen others that have just eventually fallen apart with use. I had some rubber sheet that was just about the same thickness....so I cut a disk of that to use instead of a plastic piece. It's holding so far.
- Use a propane torch to burn/melt the red loctite that they use to assemble them at the factory. Blue loctite is fine. SnapRing pliers makes assembly/disassembly really easy.
- I wipe on some grease onto the nozzle o-rings. It seems to stay in place for a good long time.
- I grease the two "slots" along either side of the bolt assembly and recoil guide rod holes.
- I loctited the screw that holds the right angle flange of the recoil guide rod to the guide rod itself. I then grease the rod/spring.
- I grease the surfaces of the charging handle

The lower receiver/mechbox are all pretty standard stuff as per the WE M4's. I would note that the receiver flange that the grip slides over/onto...is wider than the one on the M4. I can't really figure out why they would change that dimension. It'll make fitting other grips a bit of a PITA.

Additional Notes:
- I sighted in the PDW last night and the firing/action/manipulation is fine. As a "user comfort" note...I found that the fire selector arm hung down low enough when in the semi position that it kept contacting my strong hand thumb when taking a normal shooting grip. Not enough to bump it around...but definitely there.
- the rear peep sight is a bit too large for my liking, since with the short PDW stock your eye is really up close to it (which is good). I supose that the large rear apeture is actually a good thing for the intent and purpose of the PDW (quick reaction, close in, compact rifle)....but it's not really condusive to target work.
- At basement range...accuracy was just fair. Quick single shots grouped easily within a 3" black...not "airsoft" lazerific. I'll fiddle with the hopup again and see if that cannot be improved. I wonder if the poor condition of my inner barrel out of the box was an early indicator of things. I may take an "old" M4 barrel and cut/re-crown it to length and see if it produces the same result.
- Both the top and bottom screws that hold the pin that the stock attaches to the receiver should be removed, loctite'd and resecured.
- I'm thinking that the hex head screws that hold the fire selector levers on should be loctite'd too...I snugged them down for now and will see how they hold up at the game this weekend.
- when "target" shooting...there is a fair bit of muzzle jump when lightly "benching" the rifle (i.e. holding loosely on target). Full auto bursts are strong and will take you off a 3-4" target within 3-4 shots.
- WE M4 mags seemed to work very well. Solid and consistent gas strikes. The PDW mag did not seem to drop free with a mag release push...and the shots seemed "lighter" when compared to the M4 mags. Both mags insert and engage positively...there's no wondering if it really seated/caught.
- the push button female sling stud receptacles are molded into the rear receiver...they are not steel inserts as with some other setups. Other users have related that their sling swivles have disengaged in use. The ones I have (some real steel push buttons and some clones) seem to hold ok (i.e. pop it in...hold over couch, let it hang and give it a good shaking/tossing) but we'll see how the field tests go. I mounted a 20mm rail attached push button stud up front on the left rail to run a BFG Vickers 2 point sling vs. a 1 point sling.

Quickie Field Report:

I'm sure there's plenty of guys who have shot one of these longer than I have but here's a quickie field report for a new PDW (April 2011).

+ handles/shoulders/slings/deploys very quickly
+ very pointable
+ sight height is bang on perfect if you've got your cheekbone on the stock
+ out of the stock short inner barrel I got about the same range as my long inner tightbore M4 (shooting 0.30's)...maybe a bit less, but then engagement ranges were pretty tight all day. Certainly comparable.
+ nothing shook loose...although I've been advised to locktite the 6 little side screws that hold the two inter guide bars (for the bolt) to the receiver.
+ Temps were in the low to mid teens...bolt was locking back consistently
+ Feeding and cycling was 100% if the mag had gas
+ selecting fire modes was positive and sure.....the only thing that I'd like was a dead stop of trigger movement with the selector on safe. It'll let me pull about half a normal trigger pull before it stops.

- stock became a bit wobbly...not at the hinge, more so at the joints of the three sections. They're cross pinned tubes...not the strongest setup. I'm going to take a look at knocking out the pins, setting the parts with JB weld and repinning them.
- consistency in hitting point of aim was so so. I loaded my mags 4 times, 12 mags total = 1440 rounds for the day (pretty much a full coleman propane tank). I do know that the stock rubber hopup nub was/is protruding quite a bit down into the barrel even with the hopup off. From 0 field shots to ~1400 it did settle down a bit but there where still plenty of left/right fliers and most of them all had too much hop. Time to take the hopup up...look at where the wear mark is and buff the nub down to reduce the hopup.
- the stock flip up sights were good for a positive sight picture...but were really easy to flip down winding/weaving through thick brush. More than once came up to fire only to find my front or rear sight half deployed.


I'll detail more later.

At times, I've been asked what I do when I give something a "once over"...the above notes basically detail that.

Tys

[juicy]

Part 42 in my nozzle just died - the rear end of the floating-valve-esque-thing broke itself off the rest of the part. Gen 3 (originally Cansoft) M4A1 with basically no internal upgrades, short of the Stinger hop up adjuster and the green hop up rubber. Probably put around 1.5-2k BB's through it.

Can't wait for open bolt to come out now... not even going to bother with AWSS now that everything that could break has pretty much broken in mine. It's now at a point where it just won't cycle enough to chamber a BB anymore, so for the next month or so (I hope), it'll just be a damn paper weight. *WE, I hate you still.*