Hi Steve, sorry I didn't get back to you the other day - I've been out.
Ok for holdovers, you can use a program like Chairgun to calculate all the aim points for all distances, but personally I find that sometimes it can be a little off on it's calculations and just having a list of numbers in front of me doesn't make it easy for me to learn the aimpoints.
So, what I do is use these targets -
These targets need to be placed out at the correct printed range because they are graduated with Mildots at the correct size for that range.
Print those out, place them out at the correct measured distance and look through your scope to check that the mildots on the targets line up exactly with your scope.. if they don't something's wrong - also check that the 150mm marking on the targets measures 150mm - if it doesn't then you may need to adjust the Print settings in Acrobat to produce a 100% print and not "Print to Fit paper". Don't worry if it's not exactly 150mm, so long as it's close enough, that'll do.
Once they all line up, shoot groups at each distance by aiming your crosshairs at the centre of each target (the Red Dot) - you'll then be able to inspect the targets to see exactly what your holdover or holdunder is for each range - for added accuracy, make sure your crosshairs are level when you shoot. i.e. don't "cant" your gun or the results will be slightly wrong.
For example if you put the 40 yard target out and find that your pellets are all landing on the half mildot mark, then that's your holdover for 40 yards - 0.5 mildots. There's no need to measure anything and then convert to mildots, it's all done for you with the exactly sized mildot graduations on each target.
There are also a selection of killzones on each target for you to practice on - the smallest killzone on each target is the smallest killzone allowed in HFT at that distance.
Hope that helps
All the best