CZ2506- you are completely wrong.

Shooting uphill or downhill will raise your point of impact not lower it, IE if you are shooting uphill or downhill, your rifle will shoot high.


Scopes, irons etc....

If the scope is adjusted so its parallex free- most hunting scopes are supposed to be free of prrallex at 100 yards and beyond, it shouldn't matter how you hold the rifle. Unfortunately, on alot of scopes, you have to go a ways beyond 100 yards before parallex disappears. Rimfire scopes often have an adjustable objective lens so that the scope can be adjusted free of parallex at ranges short of 100 yards.

With iron sights, it matters a lot how you position yourself behind the rifle. For shooting a rifle from a bench with iron sights I lock my cheekbone against the back of my right thumb to get a consistant cheekweld. When shooting highpower matches, I usually have to adjust my sights down about 2 minutes when shooting from a sitting position as my eyes are much higher up on the rifle than if I'm shooting prone or standing. If I were gumby and had unlimited flexibility in my neck and back I would be able to get the same cheekweld as with standing, but I'm not, and most people aren't as well.

A way of looking at open sights is thinking about shooting a bow with a peep sight. In order to get comnsistant groupings, the eye, and sights need to be on the same plane every time. How archers do this is by using the same anchoring point every time. If an archer were to anchor on their earlobe with one shot, then on their chin or cheek the next, even with a peep sight, the shots will not be consistant.