Home Forums Hunting & Shooting Hunting Optics Mount Height Affecting Elevation?

OK, this is a basic trig question that has me stumped.

If you change nothing except the height of the mounts, same brand and model, just a higher version, will the point of impact be lower?

Are bigger scopes necessitating higher mounting a reason why bases with built in elevation compensation, such as the 20 minute bases, have become popular? That and longer range shooting, of course.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

Open this link TWICE change the ONLY the 'sight height' numbers on one of them, hit calculate on both, scroll down and compare trajectories one to another....

If zeroed at the same distance, trajectory will be slightly different with higher rings. POI will be a bit lower until your zero range, and higher beyond it. Play with the numbers and you’ll see just how much of a difference in trajectory mounting height makes.

I did a comparison of 1.68" and 2.2". The comparison took four hours. Both were sighted in at 200 yards. The higher rings trajectory was closer to line of sight. It almost appeared as though the higher rings had a higher velocity.

The only difference is that the line of sight is higher over the bore. Look at a scoped AR15, sight it at 25 yards and it will be a lot high at 100 yards, a typical low mounted hunting scope will be just about right for a 200 yard zero.

In practical terms it’s a pretty miniscule difference. Like previously said zeroing an AR with a scope mounted 2.7” above bore at 25 yards will cause really high impacts at 100 yards for example. When zeroed at 100 or 200 yards, theres not a big difference between small differences in ring height.

The high line of sight is more of an issue up close than at a distance.

I shot this target when I was trying to set up an AR with a light to shoot beavers at night.

The grids are 1 1/8"