on/off valve o ring question

[logit_burnit_paveit]

Okay the diagram on my classic mag shows the The big oring first then the small plastic one goes in before the Brass Valve top. I set it up this way, get about 50 shots through the gun, strip it down and everytime the small plastic oring has gone throught the big oring on top.
Is this right?

[athomas]

At the top of the on/off assembly, the small white teflon o-ring sits inside the larger urethane o-ring.