The evolution of the prototype XG-31SR [link] anti-material sniper rifle, the XG-21SR is a more compact design in a much thinner and just as powerful construction. The design features the same free-float recoiling barrel as it's original design and a more reliable loading system from a single stack magazine.
Employed on the field by S.I. (Special Infantry) it is the #1 sniper rifle of the futuristic world. It's ability to strike targets at over 1.5mi accurately and the superior ballistics of the 20mm Vulcan round make it a formidable rifle to be dealt with. The multi-function scope and integrated ballistic CPU make it fieldable in almost any time and weather conditions.
Well I've definitely outdone myself with this design After completing the first version, the XG-31, I found that a 7' 8" rifle would be incredibly hard to carry and the loading system would've been completely unreliable. Luckily by using a bullpup configuration I found I could shave over 2 feet off the overall length and a single stack magazine would create a much more reliable operation.
Unfortunately though, I wasn't able to add all the features I wanted to the design. One of which was the ability to switch between semi-automatic and bolt-action modes. But compacting the weapon and using a thinner than average chamber would've meant either a bomb in your hands or no shoulder after firing