Blue Collar Prepping has an interesting article about how to do this. It goes into more detail, and greater complexity, than the usual approach to determining MPBR, but it does so in a useful way and is well explained. Recommended reading for rifle shooters, whether novice or experienced.
If you haven’t run into the concept before, here are a few articles explaining it:
- What is “Maximum Point Blank Range” Hunting?
- Maximum point-blank range
- Understanding MPBR For Better Shooting
- Learn Your Maximum Point-Blank Range
While most shooters are at least marginally familiar with the concept of bullet drop, I've found precious few that really understand the dynamics of flight ballistics..
Line of sight is in actual fact a straight line, neglecting minor variations caused by atmospheric distortion.
Bullet flight is an arc which starts below line of sight, intersects that line at some point, continues upward to rise above it, then drops back to intersect then fall below sight line.
Since the difference between arc pf travel and line of sight from muzzle to that second intersect is at most a couple of inches most shooters seldom give it a thought, more concerned with the drop encountered at extreme range.
But for true precision shooting you should be aware of where the bullet path lies in relation to line of sight throughout the course of the shot.