20moa scope base effect on ballistic chart?

[Wes1391]

I am new to long range shooting with a scope. My primary marksmanship was the A2 service rifle with steel sights.

Using a ballistic chart 6.5prc zero at 300yards I would have a 21moa at 1000 yards. But how does a 20moa scope base change the chart calculations?

 

[spamassassin]

You've got some things wonky. The base won't change the dope, just how much up is left in your turret on that 1000yrd shot. Your zero being at 300 is highly questionable. There's only a couple good reasons to use anything but a 100yrd zero. If you're just yeeting metal nuggets at steel plates at long range then there's really no good reason to use a 300yrd zero.

So to expound on your actual question: If you need 21moa to boop the snoot of a 1000yrd distance target with a 0MOA base then you'll need 21moa with a 20moa base. Where the difference lay is if you dial in 21moa on the current setup and you have, as an example only, 25moa of up remaining then replacing your 0MOA base with a 20MOA base will mean you now can dial your 21moa of up and you'll have 45moa of up remaining.

Pick your base cant angle based on what distance you shoot and the required up to get there. You want to not have the turrets spun to their extreme limits up or down because that is the worst place, optically speaking, for it to be.

 

[Wes1391]

I assume the 20moa base doesn’t effect the ballistic calculations for bullet drop once i input on the zero distance.

 

[spamassassin]

I assume the 20moa base doesn’t effect the ballistic calculations for bullet drop once i input on the zero distance.

I guess I wasn't clear enough the first time. No, it does not. Once zeroed all offsets are relative to the zero.

 

[Raffy]

A 20 moa scope base only increases the maximum "shoot to" distance your scope can dial to on the elevation turret. There are benefits it gives you in your optic when you take in to account your scopes optical center and takes advantage of the optical center at a distance further out where it theoretically would matter more when shooting to that distance, but honestly thats a whole different discussion. I put 20 moa rails on all my rifles rather than 0 moa rails, despite knowing that my scope can dial well within the range I intend to shoot because I wanted to improve the quality of the in scope picture at a distance further out and sacrificing the optical quality nearer to me as a shooter where it arguably doesn't matter as much.