The SG 550 is a powerful semi-automatic sniper rifle available only to the Counter-Terrorists. Along with the G3SG/1, it is known as being one of the most overpowered weapons in the game despite its disadvantages. For this reason, the SG 550 is banned on many public servers rendering it useless.
The SG 550 is a heavyweight weapon. While wielded, the player's movement speed is 210 units per second (default speed is 250), meaning they suffer heavy speed reduction. While zoomed in, their movement speed is 150 units per second. The SG 550 is one of the many weapons able to shoot underwater.
At medium and long range, crouch and activate the 2x scope. Aim for the stomach and start firing non-stop. Two to three shots will kill the enemy.
If an enemy does not notice you and he is stationary, take time to shoot his head for a guaranteed kill.
Switch to your sidearm if an enemy player is too close or use the 2x scope and keep firing.
Due to the high damage, a Desert Eagle is a good backup weapon for engaging enemies at close range.
The SIG-550's accuracy is worse compared to the Scout, AWP and G3SG/1, so be sure attack an unaware enemy if he is armed with the AWP or the G3SG/1. If this is not considered, enemies with an allied sniper can easily counter your tactics.
Unlike the AWP or Scout, if the enemy uses a smoke grenade, you can fire randomly through the smoke and still have a good chance to get a kill.
Zoom in and mark the central red-dot (Counter-Strike 1.6 and Condition Zero) / center (Source) of the crosshairs with a wipeable sketch or marker pen of the color of the crosshair. This way the SG550 can be used unscoped as an semi auto battle rifle. This also works with the G3SG/1 and Scout.
Despite using a smaller cailber, SG 550 has similar effectiveness of G3SG/1 in Source.
The database file name for this weapon is sg550.
As with the G3SG/1, many servers restrict and/or ban this weapon due to its high power. These servers typically have the tag [No Auto] in their name.
The suffix Commando in its name is a misnomer as the term denotes the smallest possible derivative of a full sized assault rifle with a shortened barrel, used for close quarter engagements by special forces. Eg SIG SG 552 Commando for the SIG SG 552 and Colt Commando to the Colt M16. The term SIG SG 550 Marksman/Sharpshooter is most appropriate.