Thread: The trouble with holdovers

I was testing the trajectory of my 17HMR (17gr VMax).

I sighted it in for 50m then shot at 197m with no hold over.
This is the "tall target test".
It is true. It shows the actual trajectory in cm.
There is no distortion even if your clicks aren't exact or if your reticle or magnification are not to spec.
The result was 5 shots striking 24cm below the aim point. The group was about 4cm tall, 15cm wide and 12 cm left of midline. Wind was about 2m/s from 2 O'clock. But I'm ignoring windage because my horizontal zero was spot on at 25 and 50m.

OK 24cm at close enough to 200m is 1.2 Mils
So hold over 1.2 mil dots ...



Blurg !
4 shots are averaging 8cm lower than planned.
The problem was that I had shot on 12x but the reticle is second focal plane and is calibrated at 10x.
Those 1.2 Mil dots should be 1.2 x 20 = 24cm.
But increasing the magnification to 12x expands the target underrneath the reticle by 1.2x.
So what should have been 24cm is 24/1.2 = 20cm.
Perhaps I was holding a bit less than I should have, distracted by the half mil hashes between the dots ?
So the group was OK but not centred well enough to hit a hare at that distance.

Then there is the shot near the top of the target, pretty much 1 Mil above the other 4. Another miss !
I'm guessing I held over 2.2 mil dot instead of 1.2 mil dot. Easy to do. Looks like I did it.

So, I'm thinking it would need quite a lot of drilling and visual training to hold over every time using mil dots and its not a reliable proposition for me with a second focal plane scope.