CA yellow pistons are hit and miss. Some last forever, some blow out easily. Either way, the piston is really the "consumable" part inside a mechbox anyway and is cheap enough to replace. Otherwise though, their internals are top notch.
And on the piston note, I hear as many people having their overpriced Systema polycarbonate (red) pistons blow out. I replaced the 20k round old CA piston in my gun (that showed no wear) with a Systema. The Systema didn't even last 25o rounds before exploding. I reinstalled the CA one, and it's seen at least another 20k rounds on top of the original 20k and it's still going strong.