What does Optimum PBR zero mean in ballistics app

[a8jamesa8]

I got my ballistic app all set up with my custom load and one of the boxes on the top has "optimum PBR zero"
293
In the box just curios what the PBR and number represent?

 

[glock24]

Re: What does Optimum PBR zero mean in ballistics app

Point Blank Range

293 is the zero you should use if you want to shoot your bullet the furthest without it falling outside a specific target size window. Somewhere else in the app should be a target size dimension. The bigger the target size, the farther you can shoot without the need to adjust the scope, or hold above the target.

In other words, have you seen the deer hunters who always zero a little high at 100 yards? They do this so they can shoot further without the need to hold over their game. They are essentially trying to optimize their maximum PBR

 

[a8jamesa8]

Re: What does Optimum PBR zero mean in ballistics app

Is the vital zone radius same as the target size dimension?

 

[EMorr]

Re: What does Optimum PBR zero mean in ballistics app

It has more to do with hunting than target shooting but is applicable for both practices. glock24 got it right but I thought I would expand on what he said a little bit. The optimum PBR Zero will change with the velocity of your load and the radius of the target or vital zone of the animal you are hunting.

To make things simple let’s assume we have a .308 firing a 165 grain bullet at 2650 FPS with a BC of 0.38, at sea level. With a vital zone radius of 5” and the rifle zeroed at 100 yards. With this setup if you aim at the direct enter of the target without correcting for further distances the bullet will theoretically still hit the very bottom of a 10” diameter target at 208 yards.

Now according to my ballistics calculator the Optimum PBR Zero for this load is at 268 yards. If we zero this same rifle at 268 yards under the same conditions and again at the dead center of the target with correcting the scope for distance the bullet will hit the target at any range from 0 to 315 yards. So in review setting your zero to optimum PBR gives you a wider range of distances at which you can still hit your target without adjusting your scope or holdover.


Yes the Vital zone radius is where you would put the radius of your target if you are shooting paper.