No problem Lagopus, glad my OP helped you out. If you have any invector + cylinder and skeet tubes you don't require, please PM me as i see you are also in the UK.
Thanks to Shotgunjones for the "leade" theory, ie the point up the choke taper that the shot column hits before being constricted (if it doesn't immediately expand upon passing the step?). Thinking about that and checking my choke dimensions, i see that the lighter chokes have a greater than expected total restriction, whereas the tighter ones do not. Could this explain why the tighter chokes perhaps do not perform so well?
Does anyone have a skeet and a cylinder invector + choke they could measure to add information to this?
