Piston "O" ring?

[ginnz]

hey guys,

i have a simple question, seein' how ive never taken apart an airsoft gun 'cept mine, i dont know this.....

how tight should the "O" ring on the piston be? i mean, should it be able to flop around on the piston a bit? the last time i tore my M4 down, it was like the "O" ring is kinda oversized, like a couple millimeters of slack, kinda looks expanded, kinda like when O rings get oiled with the wrong kind of oil, they'll expand.

im wondering if this normal? the piston is ported, so it looks like when its flying forward, the ports allow the ring to expand in the cylinder for a better seal.

thanks for any input....

ginnz.

[Darklen]

Make sure the cylinder head is installed in the cylinder, put the complete piston assembly inside, including oring, put your thumb over the nozzle (the brass tube sticking out) and try to compress the piston. If the piston stops 1/4-1/3 of the way in, it's sealing properly.

Orings on the piston head seem oversized but they are meant to expand slightly during the compression stage to seal better.

[ginnz]

thanks, ill try that test next time i pull it apart. i was wondering how to check the seal.....thanks!