Stan,
Because my wife had just said my supper was ready. By the proof house charts 67.49 works out to .410" . Also from the charts, .481 is about 12.22 mm, which by the charts is between 41 and 42 ga. The answer to the question of why .410 shells would be called 36 ga would almost have to be conjecture, unless one of us did it or found documents showing why. This is like trying to explain why several cartridges with bullets from .355" to .401" are all called 38's, using only math.
Anyway, the fun is in respectful discussion.
Mike
