Echo 1 / ACM - BAR AEG - Gearbox Disassembly

[roadwarrior]

So here is a pictorial guide to reaching the gearbox of the ACM BAR.



So to remove the lower receiver you have to rotate and pullout this pin; You may need to push on the butt stock to make it come out easier because it's a tight fit:


Then pull the lower backwards, it'll stop but that's the catch so push harder until it "pops" out.


Then as you remove it rotate it downward:


To remove the gearbox remove these two screws, also keep check of the front screw. For mine only that particular screw will fit in the hole; the other one's head is slightly to big.


Also motor wiring, Check before you solder a new battery connector. I soldered the red stripe as positive but It was wired as negative. And couldn't figure out why it wasn't pulling the spring..


So now your gearbox is separated, push on the spring guide until it's flush with the gearbox and remove the pin:



The spring and guide will come out without any hassle:



Now to remove the casing take your trusty 2.5mm hex wrench and remove the 3 screws with lock washers:


As you can see I have wrapped the cylinder with metal ducttape to close the hole. works pretty good and so far o issues.


This is the tappet plate, this looks like a Ver6 to me. But I haven't taken the time to compare with my thompson.


Parts overall:

A nice polycarb piston with full metal halfteeth, I might change it to a poly-metal tooth in the future. The Pistonhead is alright, I changed the stock O-ring for a Danco #14 ring. Gears are decent with nice interlocking so for now I don't need to change those. The SHS parts fit nicely and the new bearings snapped into place unlike the china ones that just fell out when I opened the case. To re-assemble reverse the process
P.S: You may or may not need to file down the rear of the motor case to fit certain motors.


ALSO: If you change the spring guide you will need to file the sides and the "pins" flat:




Some close up pictures:

[roadwarrior]

Another thing to note is that the whole end of the barrel is separate and joined here:

And may become wobblely, this can cause the end of the barrel to be completely misaligned with the inner barrel. I fixed this by lining it up where I wanted it and put super glue in it to fill the empty space. And so far it's worked perfectly. I'd also go around and put glue over the pins just so they don't work them selves out over time.

I did try to remove the pin, but it was way too tight and decided best not to mess with it.


Update: 1/5/2013:
Magazine not feeding after some use?
This could be the possible culprit. If you look at the slanted latch that keeps the BBs in the mag you can see that there is an indention on the center and right magazine. The left magazine is perfect, The center one only has a small indention but is still workable and the right magazine's latch is completely smashed and needs to be replaced. The dents catch the feed tube and stop it from pushing the latch back to release the BBs.

Better look at the right magazine:

I suggest you spray some silicone oil in there to help keep this from happening.

[stuka]

what exactly was the purpose of the duct tape on the cylinder?

[heckman328]

You sure the cylinder head and air nozzle arent v2, bc i installed a modify v2 cylinder head and shs v2 air nozzle in it and works fine?

[warbirdguy1]

VERY good post!

[roadwarrior]

Dec 26, 2012 0:07:22 GMT -5 heckman328 said:

You sure the cylinder head and air nozzle arent v2, bc i installed a modify v2 cylinder head and shs v2 air nozzle in it and works fine?

Well it uses a V3 AK Hop so I figured V3 nozzel and head would work. They fit well so I guess there's some overlap.

Dec 25, 2012 23:50:44 GMT -5 stuka said:

what exactly was the purpose of the duct tape on the cylinder?

To close the port on the cylinder.

[stuka]

ok but what does that do?

[heckman328]

Just wondering, where did you get the shs 8mm bearings? i have been looking for a new set to replace the stock ones. I would suggest getting the prowin ak hop up it add alot of accuracy!

[roadwarrior]

heckman328
I bought them at airsoft-club.com/shop/

stuka
It stops the air from escaping increasing the FPS. Some guns need these due to their barrel length to make sure that there's not too much air being forced through the barrel. And other things, it's been awhile since I've read up on it.

[2nd Bat]

What is everyones thoughts on the bipod and carry handle? As I understand it GIs usually ditched the bipod and the WW2 BARs didnt feature a carry handle. The carry handle if left on is going to scratch the bee jeebers outta the barrel. Im assuming once loose the carry handle just slides up and off with the bipod and gas contact removed.

[heckman328]

I installed the bipod to just see how it felt with it on, and it just made the gun to front heavy. As for the carry handle, I saw many people saying not to install it because of scrapping the barrel, so I cant really say much about that.

[brownien]

If the heft of my homebuilt is similar in any way to this BAR, i prefer the bipod attached. Even though the extra weight is way far forward on the balance point, I usually only fire from the hip or prone position, making the bipod a must. If used in the correct roll as squad support, most people won't need to be sprinting up in a lightening assualt, and rather in a bas of fire squad keeping the krauts heads down. Just my $0.02

[roadwarrior]

Actually the carry handle is two pieces and clamps onto the barrel. You remove the wood handle and then separate the metal halves, place one half on each side of the barrel above the fore grip and tighten down the screws. I thought it was a swivel handle at first, so I didn't tighten it down all the way and that marred my barrel.

The Bipod is a you use it or you don't. I like it for the added weight but unless you are in a defending position you probably wont need it. I keep mine folded most of the time.

Also The shoulder plate is actually really useful when you're prone or if you have your fore arm rested against something.

[2nd Bat]

As i understand it most BAR gunners lugged the bipod when moving but often not on the gun. They carried it in their pack or left it with their duffle or the company trains where it would be brought up when they settled into a defensive posture. The carry handle is very functional and i like it alot but apparently they either werent issued with BARS in WW2 or were very uncommon. I have scoured lots and lots of pictures and havent seen any. Incidently I did see a few BARs with what appear to be Bakelight black stocks.

[stuka]

warbirdguy1 needs to hurry to disassemble his Echo1 bar to see how different the gearbox is. It's supposed to be a m240 gearbox.

[roadwarrior]

Good find! Looks like it could be dropped in without too much hassle:
www.echo1shop.com/products/echo1usa-m240b-gearbox-shell

[stuka]

more info on it from their website, it also appears to be quick spring change, does the acm have that?

www.echo1shop.com/products/ohio-ordnance-works-m1918-slr

[heckman328]

@ stuka, Yes the ACM has the quick spring change. Also I was able to just yesterday, install the prowin ak hop up unit in my BAR. It took extensive modifications, but I got it to fit snug with the gearbox, so it doesnt need to be bolted to the gearbox.

[heckman328]

Just a picture showing the prowin ak hop up unit in the BAR

Attachments:

[roadwarrior]

Update! 2nd post.

[stuka]

freaking hop-up cover got stuck =S

[heckman328]

I think I figured out how to fix the front site wobble. Underneath the front site, there are 3 very small allen screws. Just tighten those screws and it should fix the wobble. It stopped mine from wobbling, just wanted to provide what I figured it out. Hope it helps.

[2nd Bat]

It is a good idea with this gun (and most airsoft guns) to apply loctite to as many of the screws as possible. Airsoft guns fire and due to the frenetic nature by which they work, the minute and rapid vibrations tend to losen screws. Loctite makes a huge difference.

With regard to the magazine lip wearing so quickly i am not sure how silicon oil is going to help? Are you perhaps slamming the magazines into place? The wear seems rather excessive for a fairly new gun. definitely something that worries me a bit.

[roadwarrior]

I think that they had gotten grit or something in there to get them stuck keeping them from moving backwards causing the metal feed tube to smash them instead of pushing them back. Or it's just soft plastic. I think I'll get some M16 VN mid caps to replace the hicap internals along with some real bar mags.

I did try and tighten the three hex screws but they wouldn't budge for me. I did intentionally slam it on the ground a few times going prone with the bipod so...

[2nd Bat]

Its going to be interesting to see how durable the bipods will prove to be. The A&K M60 machine gun bipods have been notoriously easy to break in field use and lots of people have reported issues. In looking at the ECHO 1 (ACM) Bipod it seems to be extremely robust although the wing nuts loosen easily.

I hope the bipod becomes a seperately sold accessory like it is for the VFC BAR .

[heckman328]

I was watching the Brian at Echo1 video about how to disassemble it, and I was disapointed to see that they have no plans to release a real wood kit for it. Yes ik i can easily put a real wood handguard on, I dont want to do the extensive modifications to the buttstock to get it to fit on it.

[halfnelson]

Just recieved this Bad Ass Rifle and I'm very much pleased with it; has a meaty sound to it and the ROF is good enough for me (the closer it is to the real steel BAR the better).
One small thing though; the front end of the barrel, where the gas tube and barrel are joined, wobbles quite abit as mentioned in the above posts.
Does anyone know how I would go about to disassemble the parts around the outer barrel to get access to the space between the two barrel pieces? The gun didn't come with a manual (it's the ACM one).

Thanks alot in advance!

[HornetWSO]

The barrel sections are press fit. I dissassembled it and did not see an easy way to correct the wobble at the seam I did have good luck as mentioned above putting gorilla glue at the block where the barrel enters. No more wobble. Just ensure you straighten the barrel as the glue sets.

[halfnelson]

Ah, that explains alot! Do I have to loosen the gas tube/block and handguard and knock out the pins by the barrel/gas tube connector-thingy before attempting to disassemble it?
Would suck big time if I tried to pull it apart and murder something in the process!

[halfnelson]

Sorry for the double post, but I've managed to strip the gun down almost completely. The only thing I can't disassemble is that darn gas tube and barrel! Tight as I-don't-know-what.
I can slide the gas tube "base" (where the front pin by the hand guard goes through) forward a few milimeters, but then it won't budge. I'm afraid I'll end up cracking the "shroud" around the barrel and
gas tube if I apply too much force.