Call of Duty: Advanced Warfare has seen the introduction of multiple weapon variants of a single weapon. These variants, for the most part, have changes in their stats that from the base weapon. The following are the effects of the changes on the weapon variants.
Affects damage values (increase/decrease in damage, and which values are affected, vary from gun to gun), multipliers (XMG, RW1, and MORS), Penetration (ARX-160, MK14, and sniper rifles), Pellets (adds/subtracts one pellet per each damage point - Shotguns only).
Increases/decreases the minimum and/or maximum ranges of weapon variants by 15% (Note: On shotgun variants where the medium damage is decreased, this affects how far the shotgun can actually shoot and hit a target).
Increases/decreases ADS time by 10%, and increases movement speed by 2% (shotguns, sniper rifles, and the SAC3).
Increases/decreases Sprint-Out time (Shotguns, Sniper Rifles, and the RW1) by 10%, and Hip Fire spread by 10%.
Increases/decreases Viewkick by 10%, Idle Amount and Idle Speed (Sniper Rifles and RW1), and Hipspread by 10% (Shotguns).
Increases/decreases magazine capacity by a certain number of bullets. The associated number of bullets is deducted/added from the starting reserve ammunition, but the maximum reserve ammo is not affected.
Increases/decreases the starting reserve ammunition by one magazine. The maximum ammunition is not affected.
One should be aware that the in-game stats shown do not always reflect how the guns actually perform. For example, the Pytaek Loophole is depicted as having decreased handling (hipfire) in the stats, where as in-game it is actually increased.