Between games, store your butt packs, loaders, and hopper in the car. Refill your loaders just prior to heading out to the field. Keep in mind the exposure times mentioned above. Also, keep the paint sealed in the bag. If left in an open bag, the paint will dry out, adding insult to injury.
Some people report an above average number of balls rolling out the barrel.
This could be due to contraction if the paint is very cold. Choose a barrel diameter to suit the day's conditions. Freezing temperatures and conditions will cause dimples to appear on paintballs. Dimples will not come out of a paintball. If you suspect paint has been frozen, throw it out.