Heh Scratch........
in Critter's explanation he means.....place the reticule in such a way as to use the dots on either the verticle or horizontal cross hairs to measure (in those same dots) how many it takes to span the tyre....tyre being a KNOWN 16" diameter and the dots being a KNOWN 2 MOA each.
You can use any dots...eg.
put the end of the left side line of the reticul on the left side of the tyre and count the dots to the right covering the tyre....or, put the centre of the cross hairs on the top of the tyre and count the dots going downwards which cover the tyre....it dosn't matter.....just so long as you get how many dots to cover the tyre.......just as you would with a Mildot.
The crucial factors are..... knowing the size of the item you are ranging (The tyre) or some other item of known size near your target....eg. a car which is approximately 5 feet high.......and that the dots represent 2 MOA each.
Critter's example takes 2 dots to cover the tyre and 1 dot equels 2 MOA therefore we get a total of 4 MOA.
We then multiply the number of inches of the item of known size we are useing (the tyre) by 100.
16inches x 100 = 1600 we then divide this figure by the number of MOA, which in this case is 4 therefore 1600 divided by 4 = 400 (yards)
If we used the height of the car known to be 5 feet or 60 inches......and it was covered by 2 dots then....
60inches x 100 = 6000
6000 divided by 4 (MOA) = 1500 (yards)
You are correct about "Come up"...... it is the adjustment you make in cross-hair elevation for the range you have just calculated.
You will get the amount of adjustment you need in MOA from a balistic chart of the round you are using eg. .308 Federal Gold Medal Match 168 grain
Sorry if this is a bit "long-winded".....I hope it has made things clearer for you........cheers
