The Viper is a semi-automatic, rapid-fire sniper rifle manufactured by Rosenkov Materials. Rosenkov developed a patented automated-release system that assists with thermal-clip ejection, shortening the Viper's reload time. This rifle is popular with military snipers, who appreciate a long-range gun that can snap off multiple shots in the blink of an eye.
The Viper has changed drastically compared to Mass Effect 2. It now fires much more slowly but has more damage per shot.
The Viper, especially when fully upgraded, is the lightest sniper rifle in the game, with the Indra a close second.
The Viper is ideal for taking down groups of lightly protected enemies because its semi-high fire rate, very fast reload, and reasonably large clip allow it to rapidly kill infantry with headshots, provided a character has modded it appropriately and has the right skillset. When upgraded appropriately it can still take down moderately protected enemies with 2-4 hits to the head, with the first hit to the head often causing enemies to flinch, making successive shots easier.
In contrast with the Black Widow, the Viper fires slightly faster with more shots per clip. The reloading time is also very short, making missed shots far less costly; however, the trade off is that you have significantly less damage per shot and no cover/armor penetration without Weapon Mods, and the Black Widow is heavy, meaning that it is less suited to characters that are more dependent on their support abilities than the Viper.
The Viper serves as a good middle ground between the M-13 Raptor and the M-92 Mantis, doing more damage than the former and firing faster than the latter.
The Viper suffers a substantially lower damage penalty for firing without the scope than other sniper rifles, making it more useful to a sniper who is frequently on the move.