@Klaver The parallax effect is (in layman) when you get too close to a target with a firearm. At distances the gun's sights converge with the barrel. When you're closer there is no convergence, as such you have to aim with the barrel of the gun, not the sights. TL;DR With an AR type rifle you aim higher up if you get close.

What is the parralx free effect? And why does it only affect the ar15's?

Could you add a video please? Thanks

:)

Yay!