

No it doesn’t. The shot cup and the charge of shot travel down the barrel as a single contiguous unit. The outer walls of the cup are what contact the barrel. The shot doesn’t appreciably separate from the cup until several feet past the end of the muzzle when the petals of the shot cup are no longer restrained by the barrel. Separation is only able to happen when the cup encounters wind resistance out there in open air, and this is trivially verifiable by firing a bird shot shell at a paper target from only a couple of feet away.
This is all especially so with steel shot, because you definitely don’t want that touching the inside of the barrel. I haven’t cut a buckshot shell apart lately so I suppose it’s possible that there are still commercial loads out there that just utilize a plastic wad with no cup, but birdshot shells certainly don’t.
Edit! It was remarkably difficult to find a slow motion video of this in action: https://www.youtube.com/watch?v=1if2QKHWmU4






Another real annoyance is finding lead free air rifle pellets. Especially ones that aren’t crap, and doubly so in any caliber other than .177. Apparently it’s too much to ask to punch paper or perforate soda cans, maybe whack the occasional rat, and not be distributing lead all over the damn place.