RE: Lighter Bullets hit higher or just flatter trajectory?
Eld is dead on with this one. I had this dramatically illustrated to me with a .357 magnum. I had the pistol sighted in for dead on at 50 ft with a medium load and 158 gr bullet. Then I loaded up some screaming 110 gr bullets and expected them to hit the target several inches higher than the 158 gr. Boy did I get a surprise. The all hit about 2" below the moderate 158 gr bbl.
The reason is all in the recoil and how your body reacts with it.