This is the StR-21c, or Shark's Fin Assault Rifle.
It is a bullpup-style assailt rifle, with a grenade launcher within the forward grip. Mounted on top and fused into the weapon is a Red-Dot Advanced Targeting Gunsight, or RDATG. Below it is an ammunition counter.
It is select fire: Single-Shot/Semi-Auto, 3-Shot Burst, Full-Auto, and the G-65 grenade launcher. It fires a .35-Calibre, 3.57 mm round, which fits 45 rounds in the magazine.
If anyone wishes for me to continue this, just let me know. I'm getting good ideas of a sniper rifle to go with this. [Which is done as of now.]