Not that this answers your question (I see Roger has done that) - but after using a few boards, and adjusting fin heads to suit - I think the fin boxes are often distorted during placement in the boards: for example an iSonic 122 2008 - the box was compressed down its length, hence bulged in the middle and required the fin head ends trimming to sit flush; conversely a CA SL58 2006 - the box was slightly compressed in the sides, once sanded down the fin head sank too deep!
This is for stock and 3rd party fins - so, most likely the boxes are the problem.
So - bottom line: whether or not the fin heads are accurate, they'll probably still need to be custom fit to the board.
Regards - Martin
Last edited by MartinJE; 18th February 2009 at 04:25 AM.