Daryl;
I find that surprising as well. I would have suspect that most trap guns of that era were intended for 2 3/4" shells. Even if they were "Short Chambered" for the shell as some trap shooters seemed to prefer I would have expected them to have 2 5/8" chambers for the 2 3/4" shells. I would however have also expected that a gage of .796" would go full depth of most chambers & not give a short reading as sometimes occurs if the gage is made up to present minimum of .798".

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