I thought that I was pedantic about setting my gun up for HFT comps, but foil method?
I usually just use a vernier caliper from the centre of the loading hole in the barrel to the centre of the mounts.
Other factors like any mount packing or mounting angle inclination make more difference than say +/-0.5 mm in CTC . I have also used a vernier height gauge on a measuring table from the centre of barrel drilling to the top and bottom of scope, and subtract half of the difference to get the centre of the scope, but I realise not everyone has access to engineering measuring equipment.
Also you find that BC of pellets differs in die batches of the same pellet, and that makes just as much difference if not more.
I am currently using some AA fields that shoot almost 1/4 mildot higher at 45yards on same zero than other batches for similar velocity, so the only way to map the aimpoints out is to do the paper testing at all your ranges needed. I will have to falsify the BC figures and fps figures to match chairgun to the real aimpoints.
I can see it would be nice if you could rely on a program for scope adjustment in FT, but I would want the results testing to real tests on paper, preferably indoors to confirm it. Just my thoughts anyway.
Please let us know how close the figures turn out to actual results once you have your figures, as it is interesting if your as sad as me.