In his 2nd post, welshboy says he want's to shoot steel. I think he is doing the right thing to get the choke eased a bit. Pretty sure 1/2 choke max is recommended by most cartridge makers for steel. This is due to no deformation of the pellets, on the outside of the shot column as it passes through the restriction. So it should not be "squeezed" too much.
Yes Spot on.
just had a franchi opend out a bit ,top barrel was a tight half, and now just under, as i want to put steel through it, 25 quid