IF... such a silly question ever crossed my mind... and I hope that never happens... I'd just try holding them horizontally to see if it made any difference. I sure as hell wouldn't ask such a dumb question here.
But since you asked, I hold my barrels in my left hand at exactly a 43.7 degree angle from vertical, muzzles pointing toward the floor, top rib in the dorsal orientation, and breech end aligned with the North Star for best results. In case you were wondering, I use a cleaning rod to push my patches through, because a barrel vise just won't fit.
