Another perspective on this is harmonics that are realized as sound waves. A load that is shooting sub sonic velocities will allow the sound waves to have an effect on the entire firearm before the bullet leaves the barrel. In effect, this is really the same thing everyone else is saying about recoil effecting the POI, because it is happening before the bullet leaves the barrel. But the only real reason the lighter bullets have a lower POI is simply because they are getting out of the barrel before the effect of the waves (harmonics) can distort the barrel/firearm, not because they are heavier.
Yes, because they are heavier they do create more recoil, but that wouldn't matter if they could exit the barrel at super sonic velocity, or approximately 1000 fps, depending on the atmospheric conditions. And even this perspective is some what flawed in that how quickly the bullet reaches super sonic velocity is also a factor. Each powder produces a different pressure curve which in turn propels the bullet form zero to it's achieved speed, at different rates of gain. An example would be two dragster's crossing the finish line at different speeds, but they cross the finish line at the same time. Or one will not reach the finish line first, yet that car will have a higher rate of speed to the finish line. So the pressure curve is what really matters when trying to beat the harmonics to the end of the barrel. Usually the slower burning powders are the best performers in this respect, and IMR-4350 is deffinitely among those.
Really?
I always thought the actual direction the bullet was traveling when it left the barrel had the most effect on the point of impact.
The barrel rise being discussed is the recoil-induced movement that took place before the bullet left the barrel which, in turn, is related to the amount of time the bullet stayed in the barrel.
Longer barrel transit time, greater rise.
Lower velocity, longer transit time (or barrel dwell - thanks buck460XVR, post #11).
Heavier bullet, lower velocity.
All these suggest higher POI with heavier bullets unless you are talking about the impact at longer distances, where the bullet drop (trajectory) is more of a factor.
At some point, the two POIs will be the same (where the two trajectories cross each other's paths, as the slower bullet does drop faster), but at a farther distance than 20 yards.
Experimental results seem to agree with this assessment.
Aside from that, I don't think distortion of the barrel makes as much difference as you think. An inch or two at 100 yards, sure. But 6" at 20 yards?
I am willing to be proven wrong, with evidence.
Lost Sheep