The SC-20K has only been seen as being Sam Fisher's main assault rifle. The rifle takes NATO 5.56 x 45mm round and can be equipped with four different attachments. The rifle is capable of launching many different gadgets via the multipurpose lancher, and it has only been seen with a suppressor.
Not only can the SC-20K fire NATO 5.56 x 45mm but it also can be equipped with many different types of attachments that each serve a different purpose. Note that of the four available atachments, only the foregrip attachment cannot be switched in this fasion.
The SC-20K is a prototype based and modeled after the FN F2000. While it has many of the same features, ammo and uses that the FN F2000 has, it has been customized to include different attachments. Other differences have been noticed from the shorter rifle butt to the open space on the front of the rifle to allow the placement of the different attachments.
There are four types of attachments that can be placed on the SC-20k; The foregrip, launcher, sniper and shotgun attachments.
This attachment allows agents to use their SC-20K's with greater precision.
This multipurpose lancher attachment allows agents to launch different devices, each with its own characteristics. The launcher can shoot; All-Seeing-Eyes, Cottonballs, Sticky Shockers, Sticky Cameras, Diversion Camera's, Gas Grenades, and Ring Airfoils.
Equipped with a modified barrel, the sniper attachment fires a 20mm APDS anti-materiel round designed to penetrate hard targets and armored positions. Agents are able to hit long-distance targets with high precision. Although very powerful, it is quite loud and should be used with care.
The shotgun's main purpose is for close-quarter offensive situations. It is a semi-automatic shotgun. It also generates a lot of noise and attracts attention to agents locations.