I like odd magazines.
The composites used for the barrel are extremely stiff and heat-resistant.
Actually I didn't have a reference, it is quite similar to a random model I threw together in Pimp my Gun some years ago.
Good looking weapon, although the one thing I must point out is that the stock is far too long even when the shooter is prone which can block a persons ability to fire the weapon properly. Other than that, excellent concept.
One question though: can the barrel be folded or retracted when it goes into the Battle Mode? I ask because that kind of feature could make the rifle more maneuverable when the shooter finds him/herself in closer quarters and still retain pinpoint accuracy when folded out or extended while in Sniper Mode.
The length of the stock depends on the size of the magazine. The bigger the magazine, the longer the stock. It is fully retractable. I didn't thing about the barrel that much, being inspired by the NTW-20, I'd say that it is unscrewable or switchable to a shorter version, but unfortunately unfoldable.
When I dig through your stuff, I'd say that you also have a sleek and futuristic design approach, why don't you just switch to Sketchup? The look of its renders helps to emphasize angular and modern shaping if you ask me. BTW how do you do your designs? Are those vector graphics? Sometimes making 3D models is a little overkill when just trying to compare ideas and concepts etc, so that would be also nice to know.