What marker are we talking about? If it's an A1 there's a puff of air that comes out by the eye covers for the self cleaning eye system that's in place.
Some guy on another pb forum said it was a blow off valve. And sorry I didnt clarify, but yes it is an A1. So a puff of air blowing out is normal? Or did I just get a crappy A1 off the bst?
I would suggest reading the manual and understanding how your gun could work. Then realize that the kid that told you that there's a blow off valve inside of a paintball gun is a retard.