Rifle Scopes Help with 2 rifle one scope zero

[Danco411]

Math is not my strong suite. Can someone explain how I do this.

I have two rifles and one scope. Rifle 1 is a .260 Remington bolt in an XLR Evolution Chassis which is my 1K rifle. Rifle 2 is a Mega MKM .308 for shorter to intermediate ranges. Scope is a Nightforce ATACR MOAR in a Spuhr mount. Although I have a CQB scope for the Mega I want to be able to put the NF on it for longer range sessions with the gas gun. I need to determine the easiest way to zero one from the other. Short of just shooting it and recording the difference at 100 yards is there a way to run the data through a ballistic program to get my different elevations? I would ideally like to have a 100 yard zero for the .308 (175g SMK at 2620 FPS) and a 200 yard zero for the 260 (140 Amax at 2875 FPS). I'm sure they may even be close. How cool would that be to have them zeroed perfectly!

Little math help?

Thanks.

 

[RobertB]

Nope, you just need to shoot both with the scope zeroed for one rifle and see what you need to adjust to be good on the second one. And then test the mount to be sure it returns to zero good enough for what you want to do with it. You have a good scope and mount so you should be in pretty good shape.

 

[Dallas4rceMarine]

here are some of the factors working against you:
both guns will have a different sight to bore relationship.
your 308 has a flat rail and your bolt gun probably has a 20moa base
you have a 255fps variance in your ammo
there is roughly a .080 difference in BC between the two bullets

you are just going to have to take both to the range and take notes from your impacts. Then like RobertB mentioned you need to worry about repeatability when moving the scope back and forth between rifles. since you said the .308 was for short-intermediate distance I would give it a dedicated 1-6, 2.5-10, or 3-9. you can find those pretty cheap and you'll never have to worry about having 2 zeroes on one scope.