Reloading .303 British : Is there an Engineer in the room?

Are you familiar with something called "MPBR" (Minimum Point Blank Range)?

Basically you decide on a viable "bullseye size" (about 6" for a deer) where a hit anywhere in that area ensures a clean kill.

It will obviously vary be the size & nature of a target animal's vital area.

Now you figure out the closest & furthest point at which the rounds trajectory allows it to be in that area, initially rising up, then level then dropping back through the continuing arc till it drops to the lowest point of contact. Now come out from the closest distance  the point where the projectile is crossing down through the center line & set a center bull hold at that distance. his allows you a "center hold" over the maximum possible range. (see the diagram below if this is gibberish)

My .303 with a 150 gr @ 2450 FPS is a surprising 265 yds! Its good from about 15 yds to almost 350.

Much more detailed info here, give it a look.