Firefly "metal" rocket valve

[jplebre]

Hi guys

I'm having some problem upgrading this part.
I've put this part on a WE P226 e2. It's exactly the same size/shape as a WE plastic one (I think there might be a slight variance, but nothing quantifiable. A fraction of a milimeter, if that much).

I've changed just this part back and forward. With the stock WE part, I can shoot 2 mags before the mag "leaks out" and gives up.
With the firefly, I can shoot only 5-6 shots before the mag expels all the gas. I've gone back and forward between the two parts so I know it's down to the part as I've assembled it the same way both times.

The reason I wanted to upgrade this part was that people said it would be more durable specially when installing the nineball rocket valve spring included in the Dyna-piston set.
(the tests above are the same with or without the new nineball rocket valve spring)

Is this part a dud? hyped up? not compatible? or have I done something wrong?