[DarkAngel]

I was half dead when i posted as it was 3am, i ment inner barrels are smaller in diameter.

As for hop up used. I had no idea what hop up rubber used as you did not clarify that in your origional post. Many of us toss the Madbull Rubbers and opt for the much superior Guarder Clears (Unless your using a Madbull TB). If your unable to twist the barrel + hop up, it means theres still too much friction and not enough lubricant. Ive installed 4 of these units for clients already without any issues.

And the reason you dont slice or cut up your rubber is simple, it can compromise the shape and strength of the rubber causing it to go out of alignment with the Inner Barrel.

Also Most Aftermarket Hop up rubbers have the premoulded bump built into the rubbers. Madbull is just one of the few available. Its pretty much assumed that people will use an aftermarket rubber when they purchase a TB and a Hop up unit.

And Greenpunk is correct, do NOT use silicone oil with hop up rubbers. Itll engorge it, same with Orings.