[T. O'Heir]

"...primers cracking off..." Right. I can see and hear the excrement bricks falling now. However, dry firing doesn't involve primers going bang. It's just sight picture and trigger control practice with an empty firearm. It's also a long used training technique.
Airsoft guns are very expensive toys. A good quality air or CO2 pistol isn't. There are reasonable inexpensive bullet traps available. Midway sells one that'll stop a .22 LR(over kill to be sure for a 1 bedroom apt., but it'd do nicely for an air gun) for $63.99. The friggin' supervising cat wouldn't allow it in my place though.