Low fps with hicap mag...?

[Eldin]

So... I've finally got my fully upgraded jae 100 m14 aeg, works great!

Except for my only hicap mag, all my mid-caps and low-caps work perfectly fine, constant fps, great feeding.

But this one hicap mag is really pissing me off... the moment I stick it in the well and start shooting, the bb's just roll out of the barrel, or go about 100fps - I stick a midcap in the well, perfectly fine!

I really don't know why it's such a low fps with this certain mag!
It's a KA metal m14 hi-cap mag I believe...

Any help would be greatly appreciated.

[Styrak]

Perhaps it's pushing the hopup in a certain direction and not allowing the nozzle and hopup rubber/hopup unit to seal.

[audi_bhoy]

It's a sign, don't use hi-cap mags

As said, it might move the hop up in undesired way so it creates a leak.