additional stuff...
Staple gun with extra staples
Extra targets (I like 6" paper plates)
Duct tape (target/target stand repair)
Possibly some large zip locks to seperate your brass
screwdrivers that actually 'fit' the screws that you will attempt to turn. These are your sight screws, and not necessarily stock or grip screws. I had a Lyman receiver sight go 'ka-PING!' on my at the range, and I was just able to get back into action with my Leatherman...
Out here in Yuma, I also make sure I have good sunscreen, and plenty of water.
And of course, I too need a larger bag (I actually use a box!)
Good luck!
U. Gilbey