Yep, as part of my "Banter" that was the figures, I posted on the bore diameter. .488" for 40 & .492" for 39. Even though you asked about the 40 mark in your original post I got the impression you didn't truly appreciate us answering that part.

The actual cartridge to use could of course only be determined by the chamber cast so was not of any use to try & answer that part without dimensions from the cast.

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