Why are my POI groups at 50 yards out hitting higher than they are at 25 yards?

I always liked this video if seeing the theory is better than reading it:



https://www.youtube.com/watch?v=6rary5zbitk

For what its worth, I like to have a zero that allows the bullet to go 1/2 of the kill zone diameter. So, for a 2" KZ the bullet goes 1" high of line of sight. this gives a nice stretch of no hold over. Well, unless you aim 12o'clock edge or 6 o'clock edge of KZ. Not AG related but trajectory related, This is how I set my sons .243 dear rifle up. It is zeroed at 25yrds and will stay inside a 9" circle out to 318yrds. Haven't had one go more than 40 yrds after impact and haven't missed one yet. furthest engagement 326yrd lased. hold over was less than 1/4 Mil over 12 O'clock as he explained. 95gr Hornady soft nose BT. same principle for AG, just smaller circle.



Bill

Sight the rifles at 50 yards. 

At 66 will need 1 MOA up

At 88 will need 2 MOA's up

At 100 will need 3 MOA's up

At 30 will need 1/2 MOA down. 

This is really close for almost all Pcp's shooting at a range of 840-940 fps. 

Its a simple matter of velocity and/or scope height, and zero distance.

If your zero distance is 25yds, and your scope height is 3", youll have a second zero around 50 yds if shooting around 930fps.

Now, if you reduce your zeeo distance or increase your scope height or velocity, your second zero will be further away..

When I tried hybrid skugs at 1,000fps, my second zero went from 50yds to 65yds.

https://www.youtube.com/watch?v=VqOqZBRZsj8

Click to expand...

Not faulting the poster of the video, but the visuals in this are absolutely awful. They perpetuate the 1960 Outdoor Life depictions of rifle trajectory. A bullet never “rises” above the line-of-bore (LOB)..ever.

LOB constitutes the launch angle of the projectile. Under normal shooting conditions, a projectile begins dropping immediately upon leaving the barrel.

The line-of-sight (LOS) is normally above the LOB. LOS must be set at a downward angle relative to LOB so that the LOS intersectS the projectile trajectory at some point..or points. How you set the LOS determines whether you have one or two intersections.

With the Field Target method described by Tom, you are locating the single point LOS intersects the trajectory. Not sure what this single point is called in rifle shooting, but in archery it is referred to as your “High Pin” (HP) distance. HP can be calculated from sight geometry..peep height above arrow and peep or eye distance to your front pin At full draw..and the velocity/trajectory of the arrow. There’s no reason the single zero distance could not be calculated for an airgun.

When you have a near zero and a far zero..two points of LOS on the trajectory, the near zero distance always has a far zero distance that intersects the LOS. The mid-points between the near/far zeros are always above..impact higher..than point of aim. The advantage to a near/far zero for hunting is that you can pick a near zero that optimizes the mid-points that are within a “hit-window”..plus or minus an amount..say 0.5”..from your LOS. Chairgun has a tool that helps you pick the optimal near zero base on a target size you specify.

I didn’t watch the video but you are absolutely correct. So many knuckle heads think a bullet / pellet rises in flight. It’s not self propelled so it can’t. AlL it does is drop upon exit at 32 fps ( gravity)