This thread got me curious, so I checked the chambers on my A.J. Aubrey and American Gun Co. shotguns, thinking for sure they would be 2 9/16" chambers. But when measured with my telescoping guages and micrometers, both are 0.798-0.800 at 2 3/4" from the face of the chambers. I guess then that I can assume that both have been rechambered to 2 3/4" and should be ok with standard 2 3/4" shells? I reload with very light loads btw.