barrel porting,the long barrels....

["sigismund koster" <sigismund.koster-at-hetnet.nl>]

Hello,tankers,
i have a question about the long barrels on the tanks,for most tanks the
long barrel is a hollow tube over a paintball gun barrel(witch is much
shorter) i was thinking about the pressure for each shot,do i need to make
holes in the long tube for pressure venting? a shot from a paintball marker
can be a heavy pressure burst,and that has to pass away fast or will it
affect accuracy?
the cannon iam making at the moment is a aluminium tube close fitting over a
paintball barrel...
and has anyone used the backspinn barrels so far? they realy work!... the
ball climbs up in the air! instead of dropping.
greetings  Siggy........