Big Guns
From AoP Wiki
Big Guns is a possible primary Skill you can level up during gameplay.
It's starting value is:
Being a primary skill, it can be leveled up to 250%.
Each % increases your effective range with Big Guns. After 150%, you unlock weapon perks for Big Guns, every 25%. This means you get your first weapon perk unlocked at 150%, then at 175%, 200%, 225%, with the last one unlocking at 250% - making it quite beneficial to get it all the way up to 250%, if you are primarily using Big Guns.