Originally Posted by David_G17
here's what i was told by my grandfather:
it was originally made in 1906.
and it was designated "thirty caliber of 1906". Because there previously existed an earlier .30 cal round.
it was shortened (who wants to say all that) to "thirty of '06" (pronounced 'oh-six').
then eventually became "thirty alt six".
just easier to say i guess, but i'm no historian. that's just what i heard.
I always thought it was 30 ought 6, like in double ought buckshot '00 buck' where ought means zero.