PDI hop up-small o ring installment

Recently I have been trying to install the small o rings into the pdi hop up chamber. There are two that I needed to put in. The third, is the largest one which I can easily put on. The second largest one was an easy fit into the chamber. However, I am having trouble with the smallest o ring. I have the o ring set in a certain position. I do not have pictures but I have a link to a guy at the same spot as me: http://www.airsoftforum.com/board/lofiversion/index.php/t102401.html

If you scroll down, I am at the part with the picture where it says "almost" . My question is, what do I do after this part?

Edit: Ok, I took an unsharpened pencil and stuck it down the one side, while attempting to put in the small o ring. The pencil kept the o ring from flipping over inside of the chamber. I believe I successfully was able to install the smallest o ring. Now all three are completely installed.

Just to make sure the smallest o ring was correctly installed, should a bb be able to go through one side of the chamber and out the other. (note: this is only with the barrel and hop up chamber, not the entire rifle put together) When I place a bb in, it gets stuck at the point where the small o ring is. It shouldn't go through right? The o ring helps with compression, and since it gets stuck, that means its doing its job? The only way the bb will get through is with more compression (force) from the rifle as a whole when it is fired? If I am wrong, please help, but this is what I concluded from this morning.

Thanks

Fuzzy