Maximum point-blank range (MPBR) is the distance (in yards) a projectile (bullet) can travel without rising or falling more than a predetermined measurement above or below the point of aim. For most North American big game, from white-tailed deer to moose, an acceptable trajectory allowance is 6" (up or down 3" from the point of aim).
To estimate your MPBR, you need to know the velocity in feet per second (FPS) of the projectile as it leaves the barrel of your firearm. Divide the velocity by 10 to find the MPBR (in yards). The MPBR also is affected by whether your projectile is a conical bullet or a round ball.
- Large, heavy, conical bullet: Assume the velocity is 1300 FPS. Dividing by 10 gives you an estimated MPBR of 130 yards. This means that if you properly sight in your muzzleloading rifle at approximately 2½" to 3" high at 50 yards, the projectile (bullet) will not rise or fall more than 3" from the point of aim out to a distance of 130 yards.
- Round ball: Round ball projectiles are less aerodynamic than conical bullets. The result is about a 20% loss in MPBR over conical bullets moving at the same velocity. For example, use the same velocity for the round ball as for the conical bullet (1300 FPS). Divide by 10 to get the distance of 130 yards. Subtracting 20% of 130 (26) gives you an estimated MPBR for a round ball of 104 yards. By properly sighting in your muzzleloading rifle approximately 2½" to 3" high at 50 yards, the projectile (round ball) will not rise or fall more than 3" from the point of aim out to a distance of 104 yards.