Are you shooting F/Open or F/TR?
Ditto on most of the things AJ mentioned... clipboard and pen for when its your turn to keep score, if nothing else. Plot sheets are a good idea, especially for beginners (I still use them) but if its your first time out you may want to avoid the distraction. Shooting mat or a cheap camping mattress - not strictly necessary if the range you're going to has a grass firing line (and you don't mind getting a little damp), definitely appropriate if they have gravel or paved firing lines - less fun to lay on, etc.
If the match is at one distance, try to have basic come-ups for that distance. If thats not possible (i.e. you don't have that distance available at your home range) have a good solid zero at the max distance you do have acess to... and a half-decent estimate of MV and print out a come-up sheet. If the match is at multiple distances (say 800, 900, 1000) *write down* your come-ups somewhere you won't lose them - like inside the lid of your ammo box
DAMHIKT
One note on the food/water thing... most stateside matches don't have anything like a civilized lunch break, so think munchies, sandwiches... stuff you can eat with one hand while scoring or pulling targets with the other, or while walking during pit changes.
Bring a cleaning rod... just in case you have a squib, or a broken extractor, etc.
If shooting F/Open, I'd say fabricate a couple wood 'plates' from 1x stock or 3/4 ply about the size of the footprint of your rear bag. You may need them to get things lined up if the firing line is unlevel or the targets are above or below the firing line. Way easier to slip a plate under the bag for 'coarse' adjustment than spend forever mucking about with the front rest.
Monte
