interesting... hmm... the movie the whole nine yards? but i'm pretty sure that's not the one you were looking for..
*edited*
well.. i google'd it.. and it says "the whole nine yards" isn't a phrase whose etymology is well known.. therefore there isn't a sure meaning... a few guesses to its real meaning is... the artillery like you mentioned... the size of a nun's habit, the amount it takes to make a mans three piece suit, the capacity of a west virginian ore wagon, the length of a hangman’s noose, how far you would have to sprint during a jail break to get from the cellblock to the outer wall, the length of a standard bolt of cloth, the volume of a rich man’s grave; the distance of something associating with sports (thus where the movie comes from) the amount of concrete that fits in the mixer and the masts of the ships (yards being the spars; and 3 masts that were each 3 square yards long)
yep...
my source