Ballistics 101 - Understanding Zero

[Prime]

Just posting this for those that may have no contact with firearms or are unsure or just want a bit of education on Bullet Flight and understanding exactly what ' Zero ' is.

Once one understands Zero we can look into understanding ' HOLDS ' to allow us to make repeatable hits when the target is further out than our zero.

 

[Ystranc]

I use a deben hawk scope with subsonic reticle, it zeros at 50m so that its point of impact is on the zero at approx 25 meters and exactly 50 meters. The reticle then has increments for 75m 100m and 125m.
There is an interesting app called Xact for giving the parabolic trajectory for a given bullet design, weight and muzzle velocity. It shows how critical range is when using a .22LR compared to when using a Center fire rifle.
When zeroing I'm able to cheat, using a bench rest and a target at a measured distance of 50m. I then fire before adjusting range and windage