gas bb mp5 only fires upside down...help!!

[merc2014]

I have a gbb mp5 and for some reason it now only fires upside down.I have stripped it soo many times but after a couple of shots it goes back to only firing upside down

Any suggestions would be gratefully received.

[M_P]

Vfc?

[merc2014]

Sorry I don't understand vfc.what do you mean?

[M_P]

What make is it?

[merc2014]

Oh sorry.it's a tokyo marui.

[DEDSEC]

Most likely the magazines. If it cannot fire unless it's upside down then obviously the spring in the magazine is too weak to push the bb's into the hop up chamber.

[M_P]

Tokyo Marui don't do a gas mp5? Do you mean maruzen?

[Moose87]

Yer sounds like a BB feeding issue. Check the hop out. Try with different mags to make.sure its not just that mag.

[DX115FALCON]

sounds to me likethe magazine's spring isn't pushing the bbs up to the chamber. Try using some other mags with it.

[straffham]

Have you tried a different gas can? Could be the pressure too low, when a gas mag is filled some will be in liquid form and being heavier will sit at the lowest point of the mag. IIRC liquid gas will expand much faster than that which is already gas hence upside down it will have a lot more pressure as it will be liquid gas coming out the valve , this is shown in the white vapour cloud when fired upside down along with the action cycling much faster, (in OP case the gun fire's due to this) which is why manufacterers and retailers will tell you not to fire a gas gun upside down, it can allegedly result in destroying the gun spectacularly if higher power gas is used.

[merc2014]

Thanks for all the info guys.iv been busy at the air festival today, so I'll give it ago tomorrow. Thanks again everyone.

[merc2014]

Thank you to everyone who helped with my upside down issue.new mag sorted the issue.thanks again everyone.