Thread: How to do duel Zero. Sub/Super

Originally Posted by timattalon

The method I use is a simple Mil dot type retilcle, Then rather than do a drop chart and adjusting I simply work out the confirm what ranges the dots are for the two ammos.

EG with my 303

Load 1 Zero is at 100m and is the next dot down at about 175m (Big RN slow bullet like throwing a hammer)
load 2 is zero at 150m and the second dot down is at about 225m. (Lighter faster bullet)

If I look to what load I have in I know the distances that this load matches the marks on the cross hair. So I do not need to adjust anything regarding my scope. I just need to know what ammo is being used.

Here is a diagram of what I mean. I have simplified it a bit as while load 1 on my rifle (primary factory load 180gr doing 2700fps) is set at 40mm high at 100 metres which gives me a 200 yard zero and peaks at about 60mm at about 150m. My heavy hand loads which a re a 215gr RN SP doing 2076fps are peaking at about 40mm high at 75m with a 100m zero and fall like a stone there after. (It is only coincidence that they peak at about the same height, but it would not matter if they did not. The Sub load would peak a wee bit higher and further away if I push is out faster....)

175m is about the same low as my 250 metre point for my 180s.

I have lined up the mil dots on my diagram for illustration purposes as my scope is a little different. Rather than adjust the scope for elevation I just understand that these points are where each round passes at a known distance and that the distance is different for each of the two loads. I do the same on my 22LR for suprsonic and subs. (Zero'd at 50m for the subs and is about a 75m zero for the supers without adjusting the scope.