1. No visible rearward movement of the gun (note ports near muzzle aren’t smeared).
2. No visible effect of recoil (his cheek and shoulder aren’t displaced.
3. Unusual smoke cloud for smokeless powder. Here’s a video of a skeet competition. You can’t even SEE any smoke (start after 1:30 or so). http://www.youtube.com/watch?v=HgZqhAB2omE
4. It’s HARD to capture the moment at the perfect time when smoke is visible.
5. The vertical port smoke comes from behind the gun, with no smoke coming from the visible perforations on the left side.
6. The original of the vertical spoke plume appears about an inch wide, while the ports appear to extend about two inches along the barrel.
7. The port plume appears to originate from a single aperture source, not an elongated array of perforations.
8. Not carrying ammo like any skeet shooter.
Much of this is speculation, but would be easy to confirm by demonstration, trying to replicate the photo.
Upon further review of the photo, I conclude that there is photo evidence of recoil.