Shooting out Powertube O ring

[Toll]

This is the second oring I've managed to lose this way thus far and Im running out of them. I attempted to do a search but the words "shoot" and "power tube o ring" don't really narrow it down.


Load out :

Level 7 Pnuemag, stock level 7 spring, Emag valve.
My powertube oring is free from dents and dings, well lubed
My spacer is 215
My Tank is an adjustable AA

Issue:

The PT Oring keeps being fired out.


Am I not locking it down tight enough/need a larger spacer?

[BiNumber3]

what condition is the bolt in (particularly the part that contacts the o-ring)? and are you sure you're using the right o-rings?

[Toll]

The surface is clean and without scratches. As far as I am aware it's the correct size, its the same as the other 3 in the package