I've read before, that an arrow going 250 fps is making one complete turn every 3 feet.
That can't be "the rule". The rate of rotation per feet will vary depending on amount of helical/offset, the more helical, the faster spin rate, and obviosuly the less helical/offset, the slower the rotational rate.
I'd be curioushuntinman23, do your arrows with broadheads group? or are they all over the place?