The RSASS is a semi-automatic sniper rifle that has made it's only appearance in Call of Duty: Modern Warfare 3. It appears in campaign, multiplayer, and survival mode.
Campaign[]
The RSASS appears in campaign in the missions "Eye of the Storm", "Bloodbrothers", and "Stronghold". In "Eye of the Storm", it uniquely appears with a hybrid sight and silencer, thus making it the only sniper rifle to carry a hybrid sight.
Multiplayer[]
The weapon appears in multiplayer, being unlocked at level 44. It has a high magazone size, carrying 20 bullets, whilst making it the highest capacity of any sniper rifle in Call of Duty. It also has very a rate of fire if you have fast trigger finger. This makes a the high capacity magazine and rate of fire a deadly mix.
Survival Mode[]
The RSASS is available in Survival Mode, being unlocked at level 29 and costing $2000. It is fairly unstable during later rounds as it'll take many shots to kill.