David, Depending on which chart you use, I have seen chamber diameters at the beginning of the forcing cone of .792,.795, and ,797. All my 3.0" guns have smaller diameters than this at 3.0". The SAAMI diameter from Taylor's book is .780 at 3.0". My guns almost meet this criteria. Your guns are obviously different, however, I suspect most L.C.Smiths have slightly smaller/shorter chambers than the Hunter Arms charts indicate. Another complication is that none of the available data specifies applicable tolerances.