Stability is a weapon proficiency in Call of Duty: Modern Warfare 3. It reduces idle weapon sway by 25%. This proficiency can be considered an automatic Breath for long-range combat. It is useful on Light Machine Guns, as they need the enhanced accuracy for long-range shots, but it is also useful for Sniper Rifles, as they have the largest amount of sway. It can also be very helpful on sniper rifles when using the ACOG scope, as this attachment disallows holding breath for Sniper Rifles. However, this does not appear to significantly reduce the idle sway of ACOG and Hybrid scopes on Assault Rifles. Its effect is similar to the Ballistics CPU attachment in later installments.
Stability is a Common gun perk that appears in Call of Duty: Infinite Warfare, found upon certain weapon variants. It reduces 3% recoil while firing for the weapon variant it is applied to. Although 3% less recoil isn't very effective, this perk can be combined with grip, which reduces 7% recoil.
The Kendall 44 Cartel variant was updated to have this perk, changed from Steady, in the February 3rd, 2017 update. As a result, the Kendall 44 Advantage variant was updated to remove this perk in exchange for Steady in the same update.