LOL...now to work on punctuation
For shimming the inner barrel I used to use a little rubber oring. Then I ran out of them so I just use tape...either teflon tape or thin packing tape (the space between the inner and outer is pretty tight)
For the hopup rubbers I think the last one I put in was an A+ Studio rubber (I thought they were called MORE rubbers but maybe that was just one of their product lines).
Ratech came out with a clear or blue one too...I haven't tried that.
Ask Jugglez at airsoftparts.ca...he's my go-to guy.