Originally Posted by Robf
That is a superb little thing there!... had a go myself... got them pretty close, most within a yd, but you can see how the mistakes you've mentioned can be made (I did on the first one) and just how damned accurate and still you'd need to be (not always possible)
Something that the test doesn't illustrate and it's probably the biggest cause of inaccuracies is this...
The human eye/brain can concentrate on one thing at a time (or maybe that's just me?) so for example you might decide to use the thick part of the bottom post of your ret as the starting point for your measurements.. you concentrate on aligning the post with the top of the hinge then start looking up the ret to take a measurement. As you do this you'll find that you naturally start lifting your rifle up as well - giving you an incorrect measurement. You really need to be able to concentrate on both the start point and the end point at the same time and make sure your gun is perfectly still throughout. It's alot easier to do with a mouse on a flash demonstration than it is in real life on a course.
You only have to be out by a fraction of a mildot and you're far enough out on the range to miss the kill.
It's even worse trying to use this method in SFT out to 55 yards.. fortunately there's a more reliable method for SFT - if you're not sure how far the target is, it's probably 55 yards