OK, this is the problem: When I shoot from 30yds(in my yard) I am up higher than my target. I am getting 1 1/2" - 2" groups but, the groups are roughly 3" directly above the circle. My question is: When shooting at a target that is on a declining slope, am I supposed to aim a little lower ? Also, if I move my pin to compensate will I be shooting low on level ground?
Try it, but with only being 1 - 1 1/2', IDK what the issue is. Maybe elevate yourself, or the target, and make it even... lol.
Personally, I don't think that a shallow angle (2' drop over 30yds) will have much, if any, affect on your arrow's flight path. The steeper the angle, and the further the shot, increase change in flight. Now shooting 30 yards from a stand height of 20' downhill can be a different story. You'll start seeing a much bigger difference then. Here's some very technical info I found Arrow Flight Info
That definitely shouldn't have enough effect for you to notice. Honestly even if your range finder shows 30 yards from up in the tree to the target, there is only like a yard and a half difference (28.5) A^2 to B^2 = C^2 :d