The angle between your barrel and a straight line to the target is 3 deg. At 63' a 3 deg. At 63' a 2.8 deg. So it seems you would have to increase the perceived lead with the longer barrel to achieve the same actual lead at the target. Thanks, Lee Dear Lee, Well, I've never really looked at it the way you mention.
Most people feel that the longer the barrel, the LESS the perceived lead.
I certainly feel that way myself, though I had never bothered to figure out why the same way I never bothered to figure out how gravity worked. It seemed a pretty reliable natural phenomenon, so I let it go at that. Let' s start from the beginning. If you shoot a premounted gun with a completely flat rib, you will have absolutely no sense of barrel length. It could be two inches or two yards long.