A&K M249 Mechbox internals

[Stealthbomber]

In no particular order...

 

The A&K motor is junk. It's not unusable but it is pretty bad. Replacing it with something else will be an improvement.

 

The problem with the boxmag is simply that it only keeps up with the firing. It never beats it. I find myself drumming my fingers on the side of the boxmag as I walk out to a game, just to give it a bit of a pre-wind.

Having done that, mine's never let me down but it doesn't exactly inspire confidence.

Rather than junking the sound actuator, which actually seems to work pretty well, the best bet is to up the battery voltage from 3v to 6v. Buy a suitable 4xAA or 4xAAA battery tray in maplin and graft it into the mag.

When it's running on 6v it actually winds fast enough that it's beating the guns ROF.

You could bin the sound activation if you like and just fit a switch but I actually kinda like it.

 

For measuring ROF you need software such as AUDACITY. Plug in a microphone, record your gun firing using Sound Recorder (Start > Programs > Accesories > Entertainment) then save the sound as a .WAV file and then open it with audacity and count the number of peaks in a 1 second burst. Easy. Takes longer to say it than do it.

[Pablo]

I made a sound recording on my PC, then ran that through Audacity and counted the spikes (EDIT: beaten by SB). It was hitting 24rps at one point, though I haven't tested it since I've got it working properly with the CA high speed motor (see attached .wav file).

 

I had to swiss cheese the piston, cut a tooth off the sector gear and the last two off the piston to get mine running properly at that speed (with an M100 spring), and I've switched down to 8.4V to play it safe (with Deans connectors). Still goes like a demon (and lasts all day without eating itself).

 

Top tip: If your gearbox is still noisy no matter how well you shim the gears, I recommend replacing the anti-reversal latch with a G&P one and shim that too - made a huge difference to mine.

 

Oh, and for those who know the fun I've had getting the damn thing to feed, I've switched to a MAG box for a CA - only 1200rnds but the darned thing feeds flawlessly. I did the 6V mod to the stock box and it worked for a while but it still jammed periodically - now kept as a spare. I've also had to replace the trigger switch (though that was my fault whilst rewiring the gun). £2.39 from Maplins for a new one

[infected]

I recently had the same problems as Pablo regarding the box mag. I almost spent the money on 2 day shipping to get a CA in time for a game. Then I found the problem.

 

1) Jamming -- fixed according to FarEast's suggestion in the review thread

2) Not feeding -- Turned out the coil spring inside the box mag had broke at the end that attaches to the axel. I just bent the end into the right shape and was well on my way to some high ROF.

3) Not keeping up with the ROF -- upping the voltage in the box mag to 6v fixed it

 

Stealthbomber

You're not kidding about the stock motor. For ROF or Torque.... it stinks! I've got a Guarder High Speed motor in mine and it runs about 21 RPS if I had to guess, on my mini 9.6v battery. I'm going to put an 11.1 lipo in it soon. We'll see if the box mag can keep up with that, but I'll probably switch up to an m120

[wingzero314]

The box mag that came with mine was a junk, it has never worked in the sound mode

[ArmyofMike]

In regards to the stock piston head that comes with the A&K SAW, I was having major compression issues with mine; the piston head just seemed to float in the brass cylinder, and never actually "sealed." But I found if you place a #12 or smaller 0-ring down into the piston head crease and then on top of that o-ring place a #14 o-ring; you can greatly increase the compression and consistency of air. The stock poly piston that comes with the A&K SAW is good, and fixing the air leaks will only make it better.

 

It only takes a second to do, but has great results...

[Kye]

A little thing I did with the box mag (after I broke the stupidly placed switch) was to buy an on-off-on electric guitar switch, and install it into the back wall of the box, just in front of the trigger guard. Now I just need to extend my trigger finger forward to flick it

 

Pics:

 

 

 

 

Great information on the gearbox and internals! I'll be making notes on it all.

[Crocodilo]

Is there any "do it yoursel tutorial on rewiring the battery to the box magazine?

Thanks in advance

[lightemup99]

I have put well over 50,000 rounds through my saw without ever touching it. And last night I opened it up as the airseal had got to the point of unusable. And to my suprise the GB was in mint condition. there was zero wear on any of the gears and the piston apered to be in good shape.

 

this just reinfenforced the saying, if it aint broke dont fix it. That being said the things that should be addressed in side the gear box is the motor. I would reccomend a G&P 120 HS if you want rof. Also the O-ring on the piston was bad so that also needed replaceing.

 

But to those of you that have just purchased the gun, leave it as is, or JUST fix the two issues stated above and you will be happy you did later. I never worry about it failing at any time. And to be honest that is the best spot to be.

 

hope that helps some one.

[SgtBojangles]

EDIT - Nevermind. The sector gear my Dad tried didn't like the bearing, but it had to get along with it anyways.

 

My A&K ate a sector gear and I replaced all three gears with aftermarket ones (dunno which brand, probably HurricanE [i know, poop]). I replaced the cylinder head and the piston/head. My Dad and I tried replacing the cylinder, but there was too much suction. I think that's what destroyed the sector gear (that and wear).

 

I bought mine second hand from an "AEG graveyard" with the sole purpose of fixing it, so I guess I got what I asked for...

 

EDIT 2 - It chrono'd at 317 or so with .20's with stock everything. I'm am unsure of the RoF as I just don't care right now.

[[BS]_MARS]

I have put well over 50,000 rounds through my saw without ever touching it. And last night I opened it up as the airseal had got to the point of unusable. And to my suprise the GB was in mint condition. there was zero wear on any of the gears and the piston apered to be in good shape.

 

this just reinfenforced the saying, if it aint broke dont fix it. That being said the things that should be addressed in side the gear box is the motor. I would reccomend a G&P 120 HS if you want rof. Also the O-ring on the piston was bad so that also needed replaceing.

 

But to those of you that have just purchased the gun, leave it as is, or JUST fix the two issues stated above and you will be happy you did later. I never worry about it failing at any time. And to be honest that is the best spot to be.

 

hope that helps some one.

 

 

 

I'd have done that if I could live with constant misfeeding, terrible fps, no hop up, and the low ROF. I know what you're saying though, consider yourself lucky.

[CSAirsoftJunkie]

Sorry if this is a necropost but it seems like and on going thread. Attention readers, this is going to be long, dense reading.

 

I have given this gun countless chances to prove its worth to me, and it has failed everytime. When I first purchased it, it worked for about 10 min. Then the hopup ripped and I had to replace it. No big deal right? Well, next game I take it to, Box mag jams. No problem, just call my "hit", go back to the zone and fix it. Next game I take it to, everything is working fine. I let off about a 10 second burst( yes I know this is long) and let go of the trigger but it kept firing. Was about 30 more seconds before I could rip the battery out. Apparently just a poorly made trigger swotch, becuase I had already sufficiently trimmed it, it just got stuck in the firing position. No problem, so I buy a new trigger switch. Next game I take it to, what do you know, another box mag jam, and what do you know, It's during a 2v8 game and I'm on the 2 person team. Oh well I think. So I fix up everything. Next game I take it to, I let out a 5 second burst at a position I know the enemy is at so my team can flank them. I pull the trigger again, yet nothing happens. I call myself "hit" due to the non functioning gun. I toy with it and the battery for a bit and eventually decide just to use my TM Famas for the rest of the day. Went home and opened up the gun, discovering that the only problem was a fuze that had blown from overheating. I also found a gear with a bent axle, so I replaced that and did a perfect shim job that took me four hours. Convinced that nothing else could possibly go wrong, I bring it to the next game. In the game, I take a couple 2 second bursts, and the gun stops. I take the fuze out, put it right back in, and the gun works again. Continue playing a couple more games that day when in between games, I'm adjusting the hop-up while taking a couple shots down range. Suddenly I hear a terrible noise and the piston shreds most of its teeth off and the gun keeps on cycling. I give up. This is the worst experience I have ever had with any airsoft gun out about 60 different clones/Higher end guns/crappy springers. It was the biggest waste of money I have ever spent. It is now up for sale as is. Hopefully someone will buy this atrocity, but as of now, I am ready to get rid of it.

[Erik Cartman]

CSAirsoftJunkie,

 

I haven't read the rest of this thread.

 

I got my A&K about a year ago. The stock mag box jammed on the first burst on the first skirmish. After going home, clearing it, taking it out again next time... after a few iterations, I gave up on it. Into the cabinet goes the piece of dead weight.

 

Lately, I bought a small box mag by MAG. It worked really well. 3 day-outs stress testing with 11.1V LiPo and 5 bags of bb i.e. approx 20k rounds later on the sixth bag, the gun just stopped.

 

The positive terminal of the motor broke off. On investigation, the motor body actually had a bit of rotational play. So everytime I pull the trigger the body of the motor turns first until it has nowhere to go and then the pinion gear turns the bevel gear.

 

I thought I had to suffer the cost of a new motor, but then, I found out I could actually replace the terminal plate with a donor part. When I opened the mech box, I was amazed by the fact that the (1) there wasn't a single scratch on the rack gear and the piston was pristine. I replaced the piston head o-ring anyway. The rest of the gears were pretty accurately shimmed. (2) the green gunk grease was really disgusting. I replaced it with white lithium grease. (4) without the load of the main spring, the gear box is really easy to open and close. (5) the stock hop up nub was too short to do anything and needed replacing with a longer one fashioned out of the ink tube of a Bic ballpen.

 

All in all, I'm not too upset and I'm looking forward to taking it out again to cut some polystyrene crates (and mow down some people) next week.

 

Looking at the economics, the Mag small mag box cost half as much as the A&K M249 itself. However, that is still a lot cheaper than a CA.

 

Erik.

[Robinio]

Quick question:

Does the a&K have any spring release, so I doesn't have to be compressed all the time?

or any chance I can do it without opening the gearbox?

or is it even necessary?

[infected]

Quick question:

Does the a&K have any spring release, so I doesn't have to be compressed all the time?

or any chance I can do it without opening the gearbox?

or is it even necessary?

 

I wouldn't worry about it at all. If you're really worried about it, just pop open the back of the gun and the top. Push the lever and out pops the spring.

[Robinio]

Ok, thanks

[thewallhitme]

this weekend my mk1 was firing really low powered, so i took the spring out and it was broken in 3 places. no wonder i was getting no range!

 

any ideas why something like that would happen? all i can put it down to is thrashing the gearbox with lots of firing

[infected]

this weekend my mk1 was firing really low powered, so i took the spring out and it was broken in 3 places. no wonder i was getting no range!

 

any ideas why something like that would happen? all i can put it down to is thrashing the gearbox with lots of firing

 

I've never broken a spring. That's really odd. Is it the stock spring?

[thewallhitme]

yeah completely stock gearbox and spring! i was completely shocked when it came out. 2 coils had broken off at the rear end, and then 2 sets of 2 coils had broken off the front!

[infected]

Sounds like the spring was garbage to begin with, or not coiled properly. At least springs are cheap and easy to replace in that gun since you just pop them out the back.

[thewallhitme]

yeah, i just replaced it with one from a previous gun. simple as with the 249s