I agree- looks like tool marks in the chamber area- were there other 16 gauge shell lengths in 1905 when this Field Grade Smith was mfg'd.?? I thought back then 2&9/16" for 16 gauge, 2 & 3/4" for 12 gauge in the L.C. Smith standards--

Two things, however- (1) neither the shooter or any by-standers were hurt (although I suspect it will take a lot of Pine-Sol to get the brown greasy stains off the gent's shoes- and (2) It was a Field grade, not a A-3-- RWTF

"The field is the touchstone of the man"..