You have the choice to change to major or minor or to what ever other division you want before you fire your first round. Nothing on the sign up sheet is written in stone. Your declaration means nothing, really, unless the crono breaks or is not used for some reason before you shoot your ammo through it. Than whatever your declaration is that stands for the match. If you shot and your ammo didn't make it or was sub-minor that also would stand as long as the crono was calibrated before you shot. This just happened at the FL Open.
You could take your (minor) 8 shooter to the first stage and fire your first round and up to six rounds, than decide to change guns (if its first ok'ed by the RM) to your six shooter. You of course would still be shooting minor for the entire match. If you started with your six shooter than changed your mind, mid-match or (had a break down) and (if its first ok'ed by the RM) you could change to your 8 shooter. Than, you would if you had crono'ed already be required before the end of the match to crono again with the new gun, vis-a-vis if you please.
I wonder how many people will walk the stages in the morning to find out which to shoot 6/8? Will they than go change their category?
I really don't think you have to tell the stat's people anything at all. When you crono, they will change it to whatever you are major, minor or sub-minor if your unlucky, from the score sheet turned into them by the crono stage.
If I'm wrong please advise.