Food for thought
Every cartridge developed has a "point blank range" which is the maximum range the bullet can travel and stay within the target zone. The further the target. the lesser the point blank range.
Lets talk 30-06. 30-06 power classification with spitzer bullets are capable of a point blank range from the muzzle to 270 yds. ( able to stay within a 6" target zone ) if set up properly. Beyond this point the extended range decreases the point blank range until eventually there will be but a few feet of range that will be within the target zone.
There are volumns written on the topic of trajectory. It gets quite a bit more complicated than this explanation.
A little added info
30-06 180gr Partition @ 2700fps
Point Blank Range (stay within a 6" target)
100 yd zero
200 yd zero
230 yd zero
PBR 0-270yds (max PBR)
300 yd zero
PBR 0-65yds (65-255yds it is above target) 255-330yds
400 yd zero
PBR 0-45yds (45 - 375yds it is above target) 375-420yds