The reason people don't like Noob snipers is that in order for them to have any range advantage they need to be dangerously hard shooting and they just don't trust new guys, Also the gas rifles aren't consistent enough for a DMR or sniper really.
There isn't any "ranks" it's just respect and trust. Also there is training required at some fields so you can safely be a sniper, It has nothing to do with skill level or "rank".
Oh and one more thing, Use propane. It's cheaper Green Gas. http://airsoft-innovations.com/GunGas.html