HI and welcome to paintball, hope you have deep pockets or a good credit card
, I believe Barrells are good upto a point, but anything over 16" I believe and it will effect air efficiency. Remember Paintballs arent bullets, the longer the barrel the more time they have to bounce around and break. like others have said you dont need sights and scopes as paintballs dont fly straight, you can however see the stream as your shooting and adjust. as for a scope, im concidering getting one, not to help with my aim, but to help confirm where my target is, my biggest problem apart from being 18th stone and 6ft 2(large target) is sometimes seeing where the other guys are.