At the field I play at (Bigfoot) We had a couple incidents of people using hot guns. Mainly the new G&G Max guns. They've had to enforce random chrono tests. Our first game under that rule started something like an hour and half late since we were chronoing every gun on the field.
Airsoft is a lot like drinking. It starts off with just a few shots, but before you know it you're lying on the ground yelling for help.