AGM M4 GBB

[Downslide]

I can get you 3 mags including shipping for US$113.

 

Double the mag count, throw in a pair of ghk mags, and find a Daniel Defense version of the AGM, and you're on! (payment adjusted accordingly of course )

[Stealthbomber]

A few pics of the AGM mag...

 

First we have an empty mag.

 

Next we have a mag filled with HFC134a.

 

Finally we have a mag filled with Green gas.

 

 

The differences might not seem a lot but if you imagine a mag that's not exactly a loose fit and then you wrap a couple of layers of tape around it you can imagine it's gonna be a LOT tighter.

 

FWIW, I'd never noticed before but the mag IS pretty hard to insert even with 134a.

With propane it's definitely hard enough that I couldn't really change mags under fire at all.

[Luis21]

That's real interesting. ^^^^^

 

Maybe it's your mag that swells up alot. I haven't heard other people saying that their mag was that bad. You can always dremel/file the little channels/tabs inside the magwell.....

 

-Luis

[falconfour4]

My mags with green fit the same if they are full or empty and i havent heard of anyone else with the same problem.

[MDK_Marshal]

Sounds like you just got a lemon mag, stealth... =/

[Badly Browned]

Since Evike was out of stock on the GHK magazines, I ended up going to the local AEX and buying a Western Arms magazine.

 

First thing is that my bolt catch finally works!! I noticed that spring in the WA mag is significantly stronger than my AGM so it can actually push up with enough force to engage my bolt catch.

 

Secondly, for whatever reason. My WA mag takes quite a bit of effort to insert into the magwell. I do not have calipers to get an accurate reading, but by eyeballing it they look to have similar enough dimensions. However, my AGM does have significant paint scratches where the magwell contacts the magazine. My WA for the moment is nice and pristine.

 

I still hope to fix my AGM magazine though. What tool do I need to buy to remove those valves?

Edited June 23, 2009 by Badly Browned

[Stealthbomber]

I got bored and took mt mag to bits.

 

Turns out that the top and bottom seals were wrapped in PTFE tape.

I'm betting this is the "2nd generation" magazine that people have been talking about.

My mag has never really leaked badly even though it distorts quite a bit under pressure.

I guess that's good news for anybody who's bought a bunch of AGM mags. A 99p roll of PTFE tape should see you upgraded to "2nd generation" spec.

 

The bad news is that the release valve has always leaked slightly on my mag.

I don't have a tool to remove it yet (although I shall be making one out of an old AEG barrel very soon) but, from turning the inner part of the valve with my fingers it's obvious that there are loose and tight spots on the sealing face.

It might be that applying a bit of valve grinding compound and bedding in the valve (the replacing the o-ring, of course) will provide a better seal.

 

FWIW, I keep reading that people have leaking mags but I seem to be the only one who's mag swells up.

I'm betting these two things are connected.

If you have untaped seals in your mag then it'll leak like a bugger as soon as the shell distorts slightly. This reduces the pressure again ans so the mag doesn't flex as much.

I'm betting that once people start curing the leaks in the top and bottom seals we see more people reporting mags that swell up.

 

Incidentally, the AGM mag has heaps of internal bracing so it must be made out of TERRIBLE quality material to still stretch like this.

[mrezzy]

wow great findings guys.

 

Sooner or later we'll get good answers to fixing leaky mags.

 

Stealthbomber, when you said you found PTFE tape around the seals...do you mean teflon tape?

[Stealthbomber]

"teflon tape" is the lazy, incorrect, uneducated name for PTFE tape, yes.

[davedawg123]

You know PTFE tape doesn't actually seal, right?

 

[Luis21]

You know PTFE tape doesn't actually seal, right?

 

 

What does it do then? Because it sure doesn't tape either...

 

-Luis

 

[davedawg123]

Sorry, inside joke. Stealth knows.

Edited June 24, 2009 by davedawg123

[HSOJGNILRAD]

I got bored and took mt mag to bits.

 

Turns out that the top and bottom seals were wrapped in PTFE tape.

I'm betting this is the "2nd generation" magazine that people have been talking about.

My mag has never really leaked badly even though it distorts quite a bit under pressure.

I guess that's good news for anybody who's bought a bunch of AGM mags. A 99p roll of PTFE tape should see you upgraded to "2nd generation" spec.

 

The bad news is that the release valve has always leaked slightly on my mag.

I don't have a tool to remove it yet (although I shall be making one out of an old AEG barrel very soon) but, from turning the inner part of the valve with my fingers it's obvious that there are loose and tight spots on the sealing face.

It might be that applying a bit of valve grinding compound and bedding in the valve (the replacing the o-ring, of course) will provide a better seal.

 

FWIW, I keep reading that people have leaking mags but I seem to be the only one who's mag swells up.

I'm betting these two things are connected.

If you have untaped seals in your mag then it'll leak like a bugger as soon as the shell distorts slightly. This reduces the pressure again ans so the mag doesn't flex as much.

I'm betting that once people start curing the leaks in the top and bottom seals we see more people reporting mags that swell up.

 

Incidentally, the AGM mag has heaps of internal bracing so it must be made out of TERRIBLE quality material to still stretch like this.

 

A friend of mine has a mag that swells also when charged. It goes in nice when there is no gas in it but when full it is very hard to get in the magwell

[Frakk2k]

http://www.photostringer.com/images/bent_nose_pliers.jpg = Tool for removing valve ;D

 

I have had no problems with my mag after I took it apart. I have also kept full auto to a minimum. Just in case

[Frakk2k]

I am looking for a Magpul OD grip for my AGM, anyone know if there is a retailer with this? (Either RS or Airsoft version, I am guessing RS fits aswell?)

[falconfour4]

Here you go

http://shop.ehobbyasia.com/catalogsearch/r...amp;x=0&y=0

[Frakk2k]

Foliage Not OD

[Badly Browned]

So, I opened my magazine all the way up. The tiny O-ring in main valve had dislodged slightly out of place. I reseated it and now my AGM magazine works fine again. Mine does not have any tape anywhere in it and it does not leak on propane. Not sure what really makes these "1st Gen" and "2nd Gen" magazines people are talking about.

 

Since my AGM magazine still doesn't lock the bolt, I am getting the spring from one of my aeg midcaps and fitting it into my AGM magazine. Hopefully it will give enough force on the bolt catch to engage it.

 

 

[Stealthbomber]

You know PTFE tape doesn't actually seal, right?

 

Correct.

It just fills gaps.

 

Seriously, if you wanted to you could actually wind a length of cotton into the groove for the mag seal and then fit the seal on top of it. The cotton would pack out the seal so it works better.

I've done this on several mags and it works very well.

 

It just bugs me that people think PTFE tape seals stuff. It doesn't.

[snorkelman]

couple of things Ive not seen mentioned (might just have missed them)

 

if anyones buying upgrade parts theres no point spending dough on a steel barrel extension as the barrel extension is cast as part of the upper rather than a seperate part on these

 

despite loking for all the world like some sort of weird security screw (to the point I actually dug out a box of security tool bits) the pistol grip bolt is just an allen bolt (with some *fruitcage* awful amount of chewed up head lol)

 

It screws into a captive nut thats held in the lower rather than threading directly into the lower receiver casting

 

Bolt used looks like an m5 x0.8 thread (12 turns per cm) and around 18mm long

 

its pretty deep in so if you're using a hex key to remove it then I'd reckon a 10cm long 4mm key wouldbe minimum length

 

[Frakk2k]

A RS magpul Pmag fits fine btw.

 

(I just had to test)

[morb]

gun runs at 300 fps here on duster gas... expected a little bit more actually

But on a side note, the bolt catch works fine on duster gas?? On ultra gas it only worked from time to time..

[Stealthbomber]

if anyones buying upgrade parts theres no point spending dough on a steel barrel extension as the barrel extension is cast as part of the upper rather than a seperate part on these

Not with you here.

 

You mean the rear part of the barrel that fits into the upper receiver on an AEG?

 

Thing is, the barrel assembly for a gas M4 is unique cos it has a cut-out for the hop-up in it.

If you have a 10" CQB barrel There isn't (as far as I can see) any reason why you couldn't screw barrel extensions designed for an AEG onto it as long as they all use a 14mm CCW thread.

 

Or, are you saying that, because the alloy barrel is made in one piece, you can't unscrew the front part and fit a steel front section?

There's a variety of steel barrels available for this gun.

I bought one of the Element 5-part barrel kits that does everything from a CQB to a full-length M16.

TBH, I only want it for the CQB length section but it's nice to have all the other bits around if I ever need them.

 

Course, if you mean something else then I apologise.

 

despite loking for all the world like some sort of weird security screw (to the point I actually dug out a box of security tool bits) the pistol grip bolt is just an allen bolt (with some *fruitcage* awful amount of chewed up head lol)

 

It screws into a captive nut thats held in the lower rather than threading directly into the lower receiver casting.

Vaguely interesting this.

AGM have done the same thing in two places on this gun.

If they've done it because they accept that the monkey-metal body might not be strong enough and the thread could strip then I congratulate them on doing it this way rather than simply threading a hole in the receiver and pumping the guns onto the street regardless of whether the grips fall off in a month.

 

Course, if they've made it this way simply cos they copied the way WA made them then I guess the praise belongs to WA.

[snorkelman]

 

that bit - it fits in front of the upper receiver on the Wa and the G&P while its cast into front of the upper on the AGM

 

goiong by parts diagram I think the WA uses the captive nut to hold the pistol grip too (the ino screws in directly to the lower)

[snorkelman]

meh double post

Edited June 25, 2009 by snorkelman