A&K M249 shitty airseal?

[sushicake]

Having issues with my M249 I switched out everything in the gearbox and I can guarantee the leak isn't coming out of the piston/cylinder combo. I even switched out the original shitty hopup rubber and replaced it with a guarder clear one. But I'm still getting a massive FPS decrease even with a M110 spring.

Currently It's only shooting 340fps with that spring when it should be peaking out at 400fps which is kinda odd.

Any idea on what it could be?

[Azathoth]

The A&K uses a nozzle that is slightly different from other nozzles (it's longer for one). Go back to the stock Nozzle + cylinder head and you will have your issue fixed.

[sushicake]

But here's the problem the stock nozzle has a terrible seal and leaks with barely any effort. Same with the piston. Also I replaced it with a nozzle of the exact same length, so that shouldn't be an issue right there.

[wildcard]

Change the nub in the hop up, hop up rubber and check the hop up breech itself I have found a few of them were actually warped from the factory(bad casting) also look at the end part of your barrel some of the A&K M60 the end of barrel (hop up end) is slightly flared and deformed

[ThunderCactus]

I make custom length steel air nozzles

[Azathoth]

Are you sure your barrel is properly seated and locked into position? A&K is known for bad airseal. Assuming you have the piston/piston head sealed good with your nozzle... Every A&K 249 user that I know of, has replaced the hopup unit with a Classic army one, replaced the rubber, and tried various hopup mods to make the hopup usable.

I have a mod of my own that is better than the tinned wire solution. Not sharing

Originally Posted by ThunderCactus

I make custom length steel air nozzles

Unfortunately, this is often the best solution for some models of guns *sigh*

[Styrak]

Originally Posted by Azathoth

I have a mod of my own that is better than the tinned wire solution. Not sharing

That's kind of a dick move.

[Azathoth]

Originally Posted by Styrak

That's kind of a dick move.

It is =P I did a LOT of reading and research to help someone with a his hopup problems in his new 249 and I came up with my own solution afterwards that is better as it provides good CONSISTENT hopup. I'm sure their are other people doing the same thing and keeping their mouths shut.

:fro:

[Styrak]

Why would you be posting in a gun doctor thread/section and not want to help people?

[Azathoth]

Originally Posted by Styrak

Why would you be posting in a gun doctor thread/section and not want to help people?

I did help him, Look up several posts replace cylinder head and nozzle back to stock,and/or buy the CA hopup unit, ensure that the barrel is properly seated.

OP question is concerning airseal not bad hopup.

[Danke]

I've heard of some folks pouring silicon caulking in where the hopup chamber meets the inner barrel. Others will shim the spring that pushes the inner/outer barrel together for more pressure

Now on mine I found the outer barrel was being pushed forward.

On the outer barrel there are 2 grub screws that hold the inner barrel in place. I took those out and found a longer set. Then I took 2 of the decorative screws off the outside of the receiver, you'll know which ones when you look. I threaded the longer bolts through the receiver into the outer barrel to pin it all together. Then I put the outer screws back in place and no more movement.

[sushicake]

Originally Posted by Azathoth

I did help him, Look up several posts replace cylinder head and nozzle back to stock,and/or buy the CA hopup unit, ensure that the barrel is properly seated.

OP question is concerning airseal not bad hopup.

I've already done the hop-up mod to it, so it hops beautifully. I found out it wasn't an airseal issue it's just that running an 11.1v lipo was causing the bb's the hit each other in the barrel or just so happened to be doing that when I was chronoing it. I switched back to a 9.6v and they're shooting straight now. The was a little airleak though but I swapped out the old hopup unit with the CA one and shoved a madbull tightbore in it. So now it shoots beautiful and straight and at the right FPS.

Thanks for the tips.