[Hectic]

At short ranges with minimal environmental influence. (Wind, sun, humidity etc..) you wont notice much aside from a louder whack as the heavier bb will hold energy longer. Out doors, and over longer ranges you will have a longer effective range and less effect from the environment with a heavier weight, so long as you dont go too heavy and your hop up can provide enough spin. A good hop up on a 400fps setup is good to run .28-.32 no problem. I run .30's in all my outdoor guns aside from my bolt action. Indoors i run whatever, most indoor places should be going to a strick .20 or .25 maximum weight for safety sake, not sure if that took hold or not.