I have a 7.62x39 and added the side mount rail and an open reflex type sight.
The top rail is obviously off-center to the left. I've sighted it in at 50 yds and it holds true at 100 yds too. I expect some sort of parallax to cause the point of impact to eventually move further and further to the left as distances grow but in the distances that I've shot, it doesn't. I also expect the opposite as distances are nearer, but that hasn't been obvious either even down to 50ft. My question:
The rifling is right-hand twist which will cause a rightward horizontal drift. Does the off-center nature of the rail actually help compensate for the horizontal drift like long-ranger's have a 20MOA downward angle that helps compensate for vertical drop?
My initial belief is that even though the off-center is around 3/8th of an inch, the difference is just not enough to be noticed within the functional limits of the rifle. I'd love to try it at around 300yds or so, but those ranges just aren't available around here (begging the question, WHO CARES?) but I'm really curious whether this has made a difference for anyone.