I don't think you are understanding me.... I'm merely saying that a man's palm would make good contact at the highest point of a curved surface...and there would be les contact the further you go away from that high point .....ans consequently the print left by the contact would be good at the canter but it would fade away at the outside of the rounded surface. This is elementary....Put a glass in the freezer and when it is cold enough to form frost on the outside...place your hand on the side of the tumbler. Your hand will make good contact at the highest point on the glass but it will not come in contact with a point the is 90 degrees from that high point.
Walt, I am understanding you fine. The print does fade away at the edges as you describe where it loses contact with the rifle. The 1" tape shows that, otherwise, we would see more dermal ridges at the tape's edges, but we don't. This is consistent with the print being lifted from the rifle barrel. Otherwise, I'm not sure where you are going with this.
You seem to be implying that the print was lifted from a flat surface because it seems to match Oswald's print, which was taken on a flat surface. Trust me, you can't make any conclusions based on these images. Not unless you actually have the gumption to try and match them up. Anything less than that is a waste of time.
Here is something YOU can uniquely do. You own a MC, right? If so, you can duplicate most of these experiments and you can answer most of your questions to support your claims. You are in the driver's seat here. Wipe down your MC, disassemble it, put it in a bag, take it out and reassemble it, take a few shots, ditch it, then put on some gloves (like the DPD should have done) and test it for prints. I'll bet you get more than 0.