Well, this is quite the rite of passing for me isn't it? First fictional gun. It seems that half of deviantart is made of either Sonic the Hedgehog and fictional weapons of all types, so I guess I had to submit one after my other option (digging on the folders for ancient art) didn't turn out any results.
So yeah, this is the VS13 assault rifle, named after the fictional oblast of Rybizak. My knowledge of firearms can be summed up by "it uses gunpowder" and "or maybe it's magic" so I drew this somewhat empirically. I wanted to design something that had an AK flavor to it yet it didn't look like the AK repackages Russia loves to churn out; something with modern touches a la SCAR or XM8.
Caliber is 6.8 remington, which by my limited knowledge is good against armor, and is fed from 30-round magazines. It operates with a balanced, rotating bolt gas-operated system similar to the AEK series to minimize recoil, and I've been trying to look for ways to cram in the AN-94's lovely two-round burst thing.
The grenade launcher is aesthetically an AG36, albeit you may notice that it lacks the pivot to be opened sideways. That's because it uses the Russian GP-style caseless grenades and thus is loaded from the muzzle.
Hope it works.