If the tape is 2" then the "palm print" would have wrapped completely around the barrel, which has a circumference of 2.03 inches.....
Doe you believe it's possible to wrap your palm ( heel portion ) completely around a 5/8 " tube?
If you look at the shape of the palm print relative to the length of the tape (or the lift if you prefer) it appears to me that LHO was holding the barrel of the rifle at an angle similar to the natural way that I would pick it up. Here is a photo of a 5/8” diameter wooden dowel in my hand for an illustration:
As can be seen in my photo, the relevant meaty part of the hand wraps about half-way around the dowel. Half of the circumference of a 5/8” dowel is about 1”. However when the tape was applied to the barrel of the rifle, I would assume that the length of the tape was parallel to the length of the barrel. Therefore relative to the palm print, the lift was at that same angle as the barrel was when the latent print was left on the barrel. And because of that angle, the palm doesn’t need to wrap all the way around the barrel to span the width of the tape. We are just eyeballing the images to get a rough idea of the width of the tape. I am sure there is a more scientific way to measure these things. The tape might be closer to 1-1/2” wide than 2” wide. But I don’t believe that the reason for your theory of 1” wide is accurate.