If you use transfer port size to determine power output of a springer,

firstly its going to recoil like a "female dog"

Secondly, you're going to have problems with sealing the breach,

Thirdly, you're going to bugger up a perfectly good rifle.

Just think about it, if it was going to be so easy someone would have done it long before now.

OK you might say that not everything has been thought of yet, or the best ideas are often the simplest, which may well be true but in this instance too many people have been fiddling around with, inventing, customising and generally seeking to improve air rifles for someone not to have tried this in the past and given it up as a bad idea.

just incase you do go ahead with this you should be able to order a new compression tube from Chambers Gun Makers