ACM M500 fix (cause they won't let me post on doctors corner)

[pounce_the_jaguar]

ADMINS PLEASE MOVE THIS TO DOCTORS CORNER/GAS GUNS

OK since no one out there in the vast wastelands of the web seems to have a help guide on this gun I thought I would do one. Before you go asking what my qualifications are, let me tell you.
I have:
-Taken this gun apart more then a dozen times
-custom made my own pieces for it. SUCCESSFULLY!
-found replacement parts in the deep reaches of the web

I will tell you how to maintain, repair and keep your mossberg happy and healthy. And if you love it as much as I do, you will follow this guide.

STEP 1.
KEEP GAS IN THE DAMN SHOTGUN
I cannot stress this enough. To many times have I bought a used gas gun to find leaky seals and the such. This should be followed with every mag of every pistol you ever own. Try to keep gas in the gun all the time. That being said, the only effective way to do that is to have bbs in the chamber (ready to fire) and have a good amount of gas in it. The bb's seal off the chamber so unfortunatly you have to store this gun condition 1. If you don't keep bbs in, don't be suprised if it leaks. I've talked to a few ACM m500 owners and they all have a resivoir problem so eather keep bbs in it or gas it up regularly like me.

STEP 2.
BUY REPLACEMENT PARTS
go to airsoftgi.com and buy a pair of steel reinforced cocking arms. Those will be the first to go after the O rings. The orings will need replaceing only if you don't keeep gas in the gun. Luckily you get a baggy full of O rings when you buy the thing (like the almost knew it wasn't going to last...). If your stock cocking arms break, don't try to tape them, soder them or even weld them back together. Its no use, they are made of a shitty pot metal/plastic combination which is not ferrous enough to weld or soder. Just suck it up and buy new arms.

STEP 3.
BUY THE RIGHT BBS
I have found on many occation that my shotgun won't fire. This is not the fault of the shotgun. You didn't put it back together wrong (in most cases). Its the bbs fault. The last game I went to a buddy tried my shotgun. He loaded it with .25 bbs and fired away... to no avail of course because they bbs werent perfectly round. Buy good bbs. Again this should be standard practice, I've had atleast one gun break a piston head because of bad bbs. Now I have a jam in a gas gun for the same reason. If your gun isn't feeding its 75% of the time because of the shape of the crappy cheap bbs you bought.


MORE TO COME LATER

[Long_Bong]

Great post idear sir,

Thanks

[safx]

There's a Marushin m500 guide
complete with pictures made by
Murdoch already.

Do a search, you'll find when the
ACM's first hit ASC, there was a
big demand for it. PM him if he's
deleted the pic links.

ACM's loading tubes are flawed
compared to the real Marushin
ones, they have crowned sharp
edges, and wobble alot, which
leads to deforming and slicing of
the bbs when pushing in the tube.
You may want to sand/smooth
down the edge(s).

[mat3739]

I am so glad you posted this. I have the ACM M500 shotgun and you are right you have to search the deep reaches of the internet to find info and parts on it. My cocking arms broke on mine and I found where to buy them on airsoftgi.com just like you said but they are out of stock . However, I have found another place to purchase them. You can get them at wgcshop.com however they are out of stock there as well and double the price. It is pretty frusterating. I guess all I can do is wait until they come back in stock somewhere.
Anyway, this is a really good guide and I recomend it to everyone who has this shotgun.

[Kos-Mos]

If I remember correctly, you can also install real cocking arms for the Mossberg M500 shotgun with very little modification.

[DuffMan]

I'm having some serious feed issues with this thing. Any experts on board?

[Drake]

I've got one, worked on it quite a bit. The feeding system is pretty basic, whats going on?

[DuffMan]

Inconsistent feeding. Stick the BBs down the tubes, stick'em back in, they seem to seat fine. Perhaps I'll get a shot or two (5BBs each) off, then it just dryfires. Contrary to jaguar's post, the BBs I'm using are BBBastard, so should be alright.

I read online something about the feed ramp/wheel system not catching BBs but can't quite decipher a course of action.

Hugz and kissez

[N_Force]

I'm lazy to do the search, how is this compare to Marushin Mossberg for internal? Is it 100% clone? Thanks.

[v0nsild]

Originally Posted by DuffMan

Inconsistent feeding. Stick the BBs down the tubes, stick'em back in, they seem to seat fine. Perhaps I'll get a shot or two (5BBs each) off, then it just dryfires. Contrary to jaguar's post, the BBs I'm using are BBBastard, so should be alright.

I read online something about the feed ramp/wheel system not catching BBs but can't quite decipher a course of action.

Hugz and kissez

I just experienced this problem too. If you look down the " magwell ", you'll see that if you don't rack your gun hard enough, the wheel will stop about halfway, as the pins on the arm aren't long enough to push the arm all the way. If it doesn't go all the way, the bbs wont feed.
I was about to throw mine out in rage over it not feeding.

Pretty sure thats the reason why it happens. Haven't tested it yet though. Was planning to get some CNC cut cocking arms made, and then make the pin longer, so it pulls the arm all the way.

[DuffMan]

Originally Posted by v0nsild

I just experienced this problem too. If you look down the " magwell ", you'll see that if you don't rack your gun hard enough, the wheel will stop about halfway, as the pins on the arm aren't long enough to push the arm all the way. If it doesn't go all the way, the bbs wont feed.
I was about to throw mine out in rage over it not feeding.

Pretty sure thats the reason why it happens. Haven't tested it yet though. Was planning to get some CNC cut cocking arms made, and then make the pin longer, so it pulls the arm all the way.

If you do, you've got a customer!

[v0nsild]

Originally Posted by DuffMan

If you do, you've got a customer!

I'm located in Denmark.. you could buy the Deepfire ones from a shop in US though. It'll cost me a ton to get them here.

[DuffMan]

Hmm, gave it another look today. Not sure how to rectify this. I'm giving it a 'full' rack, each time now, but still not feeding consistently. It seems to work better when I rack it upside down, but maybe that's my imagination. Sometimes I can 'force' it to feed by twisting the trio of loading tubes at the front.