I think it all boils down to that "ignorance is bliss". After I found out my L.C.Smith 16 ga was chambered for 2 9/16", I went and bought some low pressure shells and some reloading supplies and joined the 16 ga. Relaoders Association. Also my L.C. Smith 20 ga. has 2 1/2" chambers, so I bought some 2 1/2" low pressure shells.
My feeling is why put a lot of undue stress on an old gun if you don't have to.

David