A&K M249 initial impressions

[Tarnish]

I've got a gympy sling I acquired from work that was going to sit in a cupboard forever more and I have tried it on the Minimi and I do agree it is a little on the chunky side for that particular gun. Something slimmer would be more appropriate.

[Pablo]

Great for firing from the hip though

[Tarnish]

Great for firing from the hip though 

<{POST_SNAPBACK}>

 

Oh dear I've got visions of the last part of Hot Fuzz going through my mind now!

 

[FarEast]

Mine will arrive on Wednesday, So I will start on an extensive review both internally and externally.

[rolling-thunder]

Mine will arrive on Wednesday, So I will start on an extensive review both internally and externally.

<{POST_SNAPBACK}>

That will be cool,i haven't had a chance to play with my M249 for a while now.I'm seriously thinking about buying a 9.5 v battery to up the rate of fire after seeing a video on youtube showing the differance between the standard battery that comes with the gun & a upper market battery.

[FarEast]

That will be cool,i haven't had a chance to play with my M249 for a while now.I'm seriously thinking about buying a 9.5 v battery to up the rate of fire after seeing a video on youtube showing the differance between the standard battery that comes with the gun & a upper market battery.

<{POST_SNAPBACK}>

 

 

I will also be revieweing 4 new types of motors that are to be released very soon, So i might put one in the M249 as well. But according to the manufacturer they are of the same quality and performance of the new Systema Magnum motors but half the cost!

 

They are also rated for different springs, so purchasing the right motor for the power of your gun is going to be alot easier!

[Stealthbomber]

Took mine to bits today to tidy up the gearbox...

 

First thing, maybe it's just me but I don't recall anybody else mentioning that the gearbox is running 6mm ball-bearing bushes.

It is.

Oh dear.

 

I can already feel that the bearing supporting the sector gear is a bit rough. Unfortunately, I don't have any other bushes around at the moment so the bearing had to go back in.

I assume at some point in the future it'll collapse completely and probably take the piston and spur gear with it.

 

As others have said, the gearbox has no grease in it. I stuck some in and replaced the manky copper shims with some systema ones.

 

The I came to put the gun back together.

f**king rotten bas**rd hell. What a total c**t of a job!

 

I took the trigger switch out of the gearbox and it must need to be adjusted super-ccurately. It took me about an hour to get the switch working with the trigger again.

Top Tip: The trigger switch is screwed to one half of the gearbox. You don't HAVE to remove it. Don't unless you are specifically messing with the trigger.

Also, if you need to. There's a grub-screw screwed into the top of the trigger. If you need to adjust the trigger, you can adjust this grub-screw.

 

Then there's the wires.

On the para you have to thread the wires through a small hole in th front of the receiver which you can't see because part of the feed mechanism gets in the way.

 

Eventually I poked a bit of thick wire through from the front then taped the + and - wires to it and pulled them back through. Given the size of the gun, there should be enough room inside to play football. There's no need for the thing to require fiddly , time-consuming, buggering about like this.

 

Finally, I'm not keen on the idea of the gearbox being fixed to one side of the receiver by a couple of screws. That's the sort of solution I might come up with if I was bodging a gearbox into a gun never intended to house it. You'd think CA might have figured out something a bit more elegant.

 

Anyway, it all went back together eventually and it's firing a bit smoother than before.

I'm glad it's got the quick-change spring cos I'll be quite happy to never see the inside of the gearbox ever again.

 

Oh, and it was chronoing at 350 before I stripped it down and at 380 afterwards.

 

I wonder if the "factory downgrade" just involved swilling all the grease off with parafin or something?

[RSM]

So this gun takes standard 6mm bushings? Thats a bit of a PITA, I bought some CA 8mm bearings for it expecting the bushing to be plastic....another question, how easy would you say it would be to just fold the wires to run out the back of the gun ie to go into a solid stock?

[Pablo]

Very easy.

 

I watched the takedown guide on Youtube, so I left the trigger switch alone, sorry should have mentioned it. I tied a length of speaker cable to my wires, then threaded that through the hole to pull the wires through the hole. Again, sorry should have mentioned that.

 

I thought the bearings were bigger than 6mm, though I didn't measure them. I'll be replacing them soon, so I'm glad I know now. The gun still sounds a bit whiney, but nowhere near as bad as before. I'll see if 6mil will let me chrono it and get a ROF reading on the 9.6v I'm using.

[DarkLite]

Just a heads-up: It'd be worth checking the Cylinder head and nozzle - A&K are notorious for messing them up.

 

Also, replacing the motor would definately be a step in the right direction. In my experience a CA high-speed gives about 20rps on standard gears at 1J, which can go up to 30rps if tuned right on an 8.4v battery.

[RSM]

How exactly do you check the nozzle and cylinder head? (Serious question in case it comes across as being arsey, are we just talking standard compression here or something in particular to look out for?)

 

I was originally thinking of sticking a short turbo in but then thought it would probably be better off with a G+P M120 motor and a big stonking Intellect 8.4 4200mah which should be doing something sensible rof wise on a promy M110

[Stealthbomber]

Actually, I hate to admit it but I think the bearings ARE 8mm ones.

Dunno why I assumed they were 6mm but, thinking about it, they're definately bigger than 6mm.

Bit of a "senior moment" there, methinks.

Anyway, 6mm or 8mm, one of mine IS already sounding rough so I don't think much of them, or the shims.

 

Regarding the cylinder head and nozzle...

The nozzle fits very nicely onto the cylinder head.

The brass nozzle is a very solid fit into the cylinder head as well.

 

Then we look at how the cylinder head fits into the cylinder.

Oh dear.

 

They've used a very soft nitrile O-ring on the cylinder head and they've chamfered the inner end of the cylinder.

As a result, the cylinder head barely seals on the cylinder.

 

The final snag is that the gearbox isn't terrifically cast and you can slide the cylinder about 1mm backwards and forwards inside the gearbox.

So, if you ease the cylinder back a tiny bit you can break the seal around the cylinder head.

 

To give you an idea of how borderline-dodgy this is, the A&K piston is ported and, with the cylinder head and cylinder fitted into one half of the gearbox, pressing the piston forward (with a finger over the nozzle) doesn't result in the piston coming to a sudden stop, as usual. Instead you'll get hissing noises and eventually the cylinder head will pop out of the cylinder completely.

Fortunately it all seems to be a bit more solid when you have both halves of the gearbox together but if you compare this to the way a machined alloy Systema cylinder head (with a double O-ring seal) fits into a Systema cylinder you can see that the M249 is light-years behind in terms of engineering.

 

Regarding the wires, with all that space inside the gun, would it have killed CA to put a plastic plate in the front, with a couple of brass pins on, that a couple of matching pins fixed to the gearbox to touch against.

 

Just seems totally unneccesary to have to spend half an hour buggering about with wires to get the gun rebuilt.

 

Oh and, while doing it, remember to tape the ammo carriage to the feed cover. If you don't it'll drive you f**king crazy. The feed cover lifts but the ammo carriage keeps on flopping down and getting in the in the way while you're trying to refit the wires.

 

Thinking about it, the usual problem with chinese guns it that they work OK but tend to be poorly finished.

I don't mind stuff like loose screws or improperly assembled sights. I can fix that stuff.

What bugs me is stuff like parts made from pot-metal as strong as soap and paint applied with a bucket.

It doesn't matter how clever or careful you are, you can't fix a charging handle that snaps off if you touch it.

 

Anyway, maybe cos it's mostly steel, A&K seem to have avoided a lot of these problems. The gun is finished very well and as long as you give it the once-over, there are no real "chinese-style" weaknesses.

 

I reckon if you were going to go nuts with one of these then you'd only need to concentrate on internals, particularly the piston and cylinder head with, maybe, some new gears and bearings as well. And a new motor if you want BB-hose ROF.

 

One last thing...

If you (in The Rest Of The World) want to upgrade this above 1J I'd SERIOUSLY suggest you fit a MOSFET.

The trigger switch isa only rated to 6 amps so it's not going to last forever. If you upgrade the spring you're going to melt the switch in no time. Fit a MOSFET.

There's loads of room in there for one.

 

TBH, I think I'm going to buy one for mine, even in the UK.

[RSM]

There no chance of just bunging in a new higher rated microswitch if/when the switch fails if you haven't got a mosfet installed?

[Stealthbomber]

There no chance of just bunging in a new higher rated microswitch if/when the  switch fails if you haven't got a mosfet installed?

<{POST_SNAPBACK}>

Not really.

 

Microswitches are a DIN standard item so all the ones of a particular size will be of a particular rating too.

You might find one that's rate for 8 amps instead of 6 amps but you won't find one that is rated for something useful like 20 amps.

 

I know 2 people with CA M249s and they've both had to replace the microswitch at some point. It's not a massively big job but it can be fiddly to adjust.

 

I'd bet that most people will just ignore it and then, when their switch dies (especially on tuned guns) they'll buy a new switch and then, with this advice in mind, consider buying a MOSFET.

 

The switches are only a couple of quid and they're easily available so it's not like your gun will die if you ignore my advice but a MOSFET will be the best way to make your switch last forever.

 

Don't forget that there's a guy on here selling complete MOSFET units for about £20 in the classified section.

[Pablo]

Does the o-ring on the piston head look alright to you? Seems a bit big on mine.

 

I did consider replacing the cylinder etc, but with the fps people say they're already kicking out I figured that better compression would be a bad thing.

[Stealthbomber]

Does the o-ring on the piston head look alright to you? Seems a bit big on mine.

Erm, nope. Not really.

Was it hard to get the piston back inside the cylinder?

Unless it was, it should be fine.

 

I did consider replacing the cylinder etc, but with the fps people say they're already kicking out I figured that better compression would be a bad thing.

<{POST_SNAPBACK}>

TBH, that was what I thought too.

I wouldn't be surprised to find people posting "My M249 was doing 350 fps and it's suddenly started doing 250..." threads cos the cylinder has crept backwards a bit and air can now get through the cylinder head seal.

If that happens, I'll just buy a decent cylinder head. That should sort it.

 

Like I said, I was pretty surprised (and not even in a good way) to find it was doing 390 fps after I rebuilt the gearbox.

I guess it definately needs a new spring.

Edited September 24, 2007 by Stealthbomber

[Pablo]

I changed mine for a Private Parts (honest, bought it from 6mil) M100 spring (which delivers 350fps in another gun), and it's now producing a steady 0.9j. That'll be the dodgy compression then. ROF also increased (as you might expect) but still nowhere close to a CA one.

 

The piston went in fine, there just seemed to be a bit too much "give" in the o-ring. I'll maybe open her up again tonight and check the seals.

 

Incidentally, which type of cylinder head would I want? I looked in 6mil to see what they'd got, and they had some G&P (I think) one's in but all of them were v3's. I didn't know there was a difference tbh.

[Stealthbomber]

Dunno TBH.

 

It looks like a normal V2/V3 cylinder head to me although I haven't compared them side-by-side.

 

I have a V2 cylinder head knocking around here somewhere but, TBH, I really don't fancy pulling the bloody thing to bits again to check.

 

If It was me, and I lived near 6mil, I'd rpull the gearbox out, leave it with one screw in and then take it to 6mil and then, after pulling it to bits in the shop, ask em for a suitable cylinder head.

 

Like I say, I think it's a V2 one but I'm not 100% sure. I was looking through beer goggles last night, hence not spotting that the bearings were 8mm.

[Gaffa]

OK then, ordering my MK.2 very soon, where would be the best place for me to order it from? (or preorder, w/eva)

 

I know of two so far...

Airsoft Scotland (Airsoft World) and

Actionhobbys

 

Any more does anyone know? Thanks.

[RSM]

Sorry for being a question machine at almost every step, but how easy would you say soldering a mosfet in will be or where would I be looking to solder it in? The instruction sample over at the classifieds doesn't seem too clear to me. What I mean is, is it a case of if you know what you are doing with a soldering iron is it a case of 'solder that bit here, solder this bit there, put the mosfet somewhere there's space and you're good to blat off an entire box mag' or is there more than that to it?

[Pablo]

Got a link? I know naff all about mosfet's, should check 'em out.

[RSM]

Its these I'd be looking into, the ones Stealthbomber referred to

 

http://www.arniesairsoft.co.uk/classifieds...uct=669&cat=all

 

But suddenly I'm all confused but the extra wiring

[Pablo]

Cheers, saved me hunting. Have an imaginary +10

[Gaffa]

More pics from the installation guide:

 

http://i104.photobucket.com/albums/m162/KP...OSFET/Page1.jpg

http://i104.photobucket.com/albums/m162/KP...OSFET/Page2.jpg

http://i104.photobucket.com/albums/m162/KP...OSFET/Page3.jpg

http://i104.photobucket.com/albums/m162/KP...OSFET/Page4.jpg

http://i104.photobucket.com/albums/m162/KP...OSFET/Page5.jpg

http://i104.photobucket.com/albums/m162/KP...OSFET/Page6.jpg

http://i104.photobucket.com/albums/m162/KP...OSFET/Page7.jpg

 

This page may also help..

 

http://www.airsoftmechanics.com/home/conte...category/13/30/

[zombe minge]

has anyonehad a chance to crono there guns yet and if so what was the fps , am goin to site at weekend and there limt is 328, i need to know if i should down grade and what spring do i need for this thanks .