Like Pete says you really need 2 guns with the same power and the same pellet in the same wind. Both rested and see what the difference is. Ideally you want MV and downrange velocity measured, so it's back to Bri's downrange chrono.
I've always found forecast wind speeds to be confusing. I've seen forecasts of say 10mph and if you look at CG you see quite a suggested drift at 10mph at 45 yards. You never seem to get that, even on a target where you are at 90 degrees to the wind. The wind will often be sheltered by trees, shrubs etc. It is also always variable and we ( when you've been shooting for a while ) tend to just wait until we feel that dip in the wind. However you've stated that Ian was giving it more than you. Maybe the guns or maybe you are more trained to letting the shot off when you spot that dip.
It will be interesting at places like Quarry and Rivi to see if it's a windy day and the top, non BSA guys, have struggled to get over 50, if the Goldstar top shooters have coped a lot better and scored mid/high 50's.
I can see a few targets where those cross hairs are a few dots outside the kill and if the target goes down the BSA boys claiming ... " Yup ... inside left edge again on that one ".
Sounds really interesting though. I've had my grumps over BSA 0.177 barrels but I really do hope these rifles do well. Good luck with them.