Every 0.75 seconds you Aim Down Sights increases your Bullet Damage by 10% (up to 3 stacks).

+ 7.5% Bullet Damage + 200% Bullet Penetration

+ 10% Bullet Damage + 15% Effective Bullet Range

+ 25% Damage - 30% Health

+ 30% Rifle Ammo Capacity + 10% Damage with Assault rifles and LMGs

+ 50% Weakspot Damage - 40% Move Speed while shooting or melee attacking.

+ 30% Weakspot Damage - 5% Damage Resistance

Each bullet hit causes the target to take 1% increased damage for 3 seconds (stacks up to 15%)

+ 5% Bullet Damage + 1.5 Bullet Stumble Damage + 7.5 Melee Stumble Damage

Pain Meds you apply also grant + 25% Damage for 60 seconds.

+ 75% Ammo Capacity - 5% Move Speed