Trajectory Based Black Bull Size For Scaled Air Pistol Target

[Random Plinker]

Scaled reduced distance target scoring rings have to take into account the fact that shooting at a closer distance does not make the diameter of the pellet smaller: (http://www.gatewaytoairguns.org/GTA/index.php/topic,16628.0.html).

But we all know the "right" way to scale the size of a black bull for a reduced distance target is to multiply the regular distance target black bull diameter by the ratio of the new scaled distance to the original distance, right?  The black bull is used for aiming, not scoring, and this makes the black bull appear the same size at the reduced distance.  So at 5 meters, the 59.5mm black air pistol bull on the 10 meter target would be 5/10*59.5, or 29.75mm.

But what if you do not want to adjust your sights between shooting at a reduced distance and shooting at the normal distance?  Well, I did some calculations this morning with Chairgun and plotted the results in the attached pdf file to find out.  Pretty interesting stuff, if you suffer from a touch of OCD and like this sort of thing!

The first case is a 0.011 BC wadcutter pellet fired from my trusty Crosman 2300T with a front sight post about 11/16" above the center of the barrel at ~500 fps.  For a 6 o'clock hold, it looks like I want a black bull about 20.5mm in diameter at 5M if I don't want to adjust my sights from their 10M shooting elevation, which is closest to the 8 ring on a 5M target.  The other cases show sensitivity to muzzle velocity and sight height.

I think I still like the black bull to appear the same size at 5M as 10M, but I plan to try out a smaller black bull out to the 8 ring and see what happens.  I mostly shoot up close at 5M, and cannot shoot well enough to notice the pellet diameters of a difference it may make at 10 meters if I become too accustomed to centering my shots on a 5M target with a 29.75mm diameter black bull.