OK!Well I am just too lazyzzz, and too often away from home.
Will take dimension of the O-rings ASAP.
I can say that dimension of the O-rings are not that important. I have used O-rings slightly different, and the system works anyway.
Actually I use this system only on short guns now.
For the long guns I have switched to vacuum muzzle...
... made in Ucraina!
Do you use "Kalipso" (UBL) system?