Not designed for 3000 psi is an understatement. Slidechecks are used for 150psi air. We manufactured paintball ones for 800 psi for years. Both safety and function go out the window over 1000.
I'm sure that's written in a character/pictorial language on the website I bought them from
A lot of PB guys carry carbon tanks now; for extra supply. The bottles hoses and regs are usually rated to 3000 or 4500psi as they fill at scuba shops as well.
You are correct about bottle pressure and regulators. Paintball guns operate on 800 psi max (co2 pressure). The modern electronic guns usually run on 250 or 400 psi supply, which is all the slidecheck would see. The remote lines aren't used to refill the tank; they are used to feed the gun.
