It sounds like the bucking might have been installed incorrectly. When you say bb's are powering down, do you mean there is no hop? Please elaborate, as I encountered many PDI hop up problems, and any details will help me help you.
Not sure about the small o ring ripping in half. All I can think of is if you did not get it installed completely/correctly, resulting in the bb, when fired, to slam against the o ring, causing the o ring to rip.
I would suggest getting your hands on a PDI repair kit, as it will supply you with spare o rings. And try not to get too frustrated. I know the feeling, and I had to get my hands on a few repair kits as well. Took some time before I figured everything out.
Not sure about the small o ring ripping in half. All I can think of is if you did not get it installed completely/correctly, resulting in the bb, when fired, to slam against the o ring, causing the o ring to rip.
I would suggest getting your hands on a PDI repair kit, as it will supply you with spare o rings. And try not to get too frustrated. I know the feeling, and I had to get my hands on a few repair kits as well. Took some time before I figured everything out.