I always just show up a bit early and zero it before the game if I need to. Once you're dialled in you shouldn't really need to adjust anything unless you change something up.
The longest part of your house is probably the next best thing but it's only so effective unless you have a massive hallway. Make sure you're not breaking any laws if you choose to use your backyard.
edit** There aren't really any airsoft ranges, sounds to me like your best bet is to do it before a game.
Last edited by Kozzie; June 10th, 2012 at 18:01..