What is a hop up for airsoft guns?
"Hop-up" on airsoft guns can be either adjustable, or is already
put in the gun. What adjustable hop-up is, is a switch usually on
the side of your gun that you can control the amount of backwards
spin the bb has when it comes out of the barrel. The more spin
backwards, the better, this means the bb is going to fly
straighter, farther, and more accurate because when it goes through
the air, the backwards spin keeps it floating. I would suggest a
gun with adjustable because you can judge your shots. ( by the way,
hop-up that is already in the gun means you cant adjust it, it
stays how it is)