When it comes to snipers, they have the Highest Max damage and range, But overall. if you get a 4x4 scope with a AR, or anything really! then boom you have a Sniper!
then it kinda wrecks the role of the sniper.
SO here is a Idea
Sniper rifles should have a Longshot bonus. when you hit a zombie at a point of range. like maybe 850M. you will get a Longshot bonus!
the Base extra damage is 3.5x but when the marksman perk reaches 3, 4 and 5 it will go up by 0.5 so it will be 5x. and with the sniper perk it can go up by another 0.5 so. 5.5 with all perks and books!
So being a Sniper will serve a better role