Note that he said this was a 315. I can't recall for sure now as many times as this has been posted, but were the early 311's built on the 315 design. The picture clearly shows the rear cross pin higher than the front one which would make it the 315 design. It was most likely built for the shorter shells & lighter loads.
I am in full agreement with 8-Bore, If I were shooting at 40 yards I would not want a .410.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra