A&K M249

[Uchiha Itachi]

Alright, before I gut this bitch again what could be causing this.

This is either a V. 1 or V.2 A&K M249

It sat for a few months, but prior to sitting it worked ok. However, a month ago we started using it again. This is what's happened:

--FPS was around 160, troubled shot problem to hopup o-ring being bad. This brought the FPS to 220.
--FPS is now 220ish, I figured the O-ring on the Piston head is bad as well given the condition of the hop-up Oring. I tore open the GB, swapped it for a new O-ring, closed it, then re-installed. Chrono'd at 300-305 before the game, then 290-299 after the games.

So, this leaves me with 3 problems.

A) The spring is bad
B) The piston head is bad
C) Both are bad

Ideas, or am I just going to have to replace the upper assembly to fix this?

[yammie r6s]

your fps inconsistency should point out where your problem lies in general... asuming it's all stock you have an air seal issue

check the inside of your cylinder for scores that would damage your o-ring - normally there is no reason at all why an o ring should go bad besides from A LOT of wear and tear use. but you could have had a faulty one to begin with

check your seal between your cyl head and cylinder (some have orings there as well) should be a nice tight seal

go buy some rc shock oil and lubricate your piston head o ring with it.. don't use any other kind of lube either

[Uchiha Itachi]

About a day after posting that, I tore it apart and replaced every seal I could find while digging through all the guides for one.

It appears the problem was the top end isn't very well made. The cylinder head had a bad seal(replaced with a slightly larger seal) and the cylinder doesn't sit right in the GB. There is a 1mm gap between the cylinder and gear box. Even with the new seal I can still feel a tiny bit of air escaping from there when it cycles back. The whole piston assembly doesn't really fit right into the cylinder.

The piston head is also pretty sketchy with the groove being too deep. I'll end up replacing all the piston parts+head the next time it breaks.

All the O-rings were bad. The hopup O-Ring was cracked, the Piston O-ring was flimsy and too small, and the cylinder one was also too small and nearly severed when I took it off. The gun had less than 2k through it given the never ending problems we've had with it and the box mag.

[busta_cap]

That's China quality for ya.

[Whiskey11]

About a day after posting that, I tore it apart and replaced every seal I could find while digging through all the guides for one.

It appears the problem was the top end isn't very well made. The cylinder head had a bad seal(replaced with a slightly larger seal) and the cylinder doesn't sit right in the GB. There is a 1mm gap between the cylinder and gear box. Even with the new seal I can still feel a tiny bit of air escaping from there when it cycles back. The whole piston assembly doesn't really fit right into the cylinder.

The piston head is also pretty sketchy with the groove being too deep. I'll end up replacing all the piston parts+head the next time it breaks.

All the O-rings were bad. The hopup O-Ring was cracked, the Piston O-ring was flimsy and too small, and the cylinder one was also too small and nearly severed when I took it off. The gun had less than 2k through it given the never ending problems we've had with it and the box mag.

Solution:
You will need an account (You do have one dont you? I thought you did?)

http://www.arniesairsoft.co.uk/forums/i ... 176568&hl=

That should solve any airseal issues between the hop up rubber, hop up unit, and gearbox.  I think  If not, it was worth a shot.

[Uchiha Itachi]

Solution:
You will need an account (You do have one dont you? I thought you did?)

http://www.arniesairsoft.co.uk/forums/i ... 176568&hl=

That should solve any airseal issues between the hop up rubber, hop up unit, and gearbox.  I think  If not, it was worth a shot.

That is where I discovered the Cylinder problem. I'm just going to get some sealant that won't eat the plastic or pot metal shell. If it still has an airleak, I'm going to have to start replacing parts.


busta_cap

I've owned probably around 20 higher end clones. The only clones to give me problems were guns not cloned from another company. I just avoid those brands now(2).

The only issues I typically have from clones are from previous users lying. It's why I no longer trade/buy used guns but this isn't solely a clone issue.

[busta_cap]

Solution:
You will need an account (You do have one dont you? I thought you did?)

http://www.arniesairsoft.co.uk/forums/i ... 176568&hl=

That should solve any airseal issues between the hop up rubber, hop up unit, and gearbox.  I think  If not, it was worth a shot.

That is where I discovered the Cylinder problem. I'm just going to get some sealant that won't eat the plastic or pot metal shell. If it still has an airleak, I'm going to have to start replacing parts.


busta_capYeah.. It's easier to reverse engineer a gun that is built to last, but building from the ground up is a bit different..the other thing I should elaborate from my necro post was that the Lemon, or just weird random crap that happens to Clones factor is more evident in guns that are not of a more reputable brand. You can't really complain though..its a sub $300 M249..

I've owned probably around 20 higher end clones. The only clones to give me problems were guns not cloned from another company. I just avoid those brands now(2).

The only issues I typically have from clones are from previous users lying. It's why I no longer trade/buy used guns but this isn't solely a clone issue.

[Uchiha Itachi]

Yeah.. It's easier to reverse engineer a gun that is built to last, but building from the ground up is a bit different..the other thing I should elaborate from my necro post was that the Lemon, or just weird random crap that happens to Clones factor is more evident in guns that are not of a more reputable brand. You can't really complain though..its a sub $300 M249..

I've had an A&K SR-25, CQBR, and MK43. All worked perfectly fine and had zero issues. This thing just came with a broken box mag, weak mag spring, horrible compression, and some manufacturing defects. Even with these problems fixed, it is still well cheaper than a CA M249. I could throw in a bunch of upgrade stuff, that the CA would also need, and it would still be much cheaper.

I just happen to get that 1 with issues.

[Uchiha Itachi]

Does anyone know if the newer A&K/Echo1 Hop up units are better?

This PoS STILL doesn't work.. The GB is fine, nothing is cracked, worn, broken, or damaged. You can't even tell it's been used. But, the hop up is blowing air out the front and through the dial. I've changed the o-ring and checked the rubber for tears...this hop up unit just doesn't work. I can't do the fixes listed on Arnies, nor can I find any in stock CAs.

The only thing left to do is pre-set and glue the damn thing.

[MLA PRO]

The same thing happened with my CAm15a4 sportline. It was chronoing at 190fps with and m120 spring. I took out the gearbox and reset everything. It upped the fps to about 230ish. I got an idea from a reliable source, it was my oring and my piston head. After fixing that, i shot once, it worked perfect, shooting about 400ish, then the second shot my sector gear stripped, i guess my gears werent strong enough? I bought a new gear set and its shipping in on monday im guessing. Hopefully it will work.
Thats just my similar story.

[Uchiha Itachi]

There isn't anything wrong with the GB. There is several times more air pressure coming out of the nozzle when the barrel isn't attached. Even on auto the pressure remains the same. It's only when the hopup/barrel is attached does the air pressure tank.

Given Echo1 and A&K M249s are the same, I was wondering if the latest hopups don't have the issues this one does. Given the problems, a new bucking won't help it.