Yeah, that's what I was afraid of. Usually a sight with a dovetail mount isn't illegal, but clubs can set their own rules in unsanctioned shoots. Like I said, you need to contact the folks in charge of these tournaments and ask them about your sight, specifically, to get the rule clarified.

By the way, do it by e-mail, not over the phone if at all possible. I know of too many people that have gotten verbal okay over the phone, only to show up and not be allowed to shoot in the class they wanted because their equipment wasn't allowed. If you've got e-mail verification, print it off and take it with you. That way you can tell them you had your equipment pre-approved if you run into any hassles.