Similar critique as in this one http://www.blenderartists.org/forum/showthread.php?371117-First-Time-Rendering-with-a-texture&p=2870482&viewfull=1#post2870482
The gun silhouette is not strong enough to identify what type of weapon it is: handgun, assault weapon (held with two hands) or a rifle. The grip and trigger size and position suggest it’s a handgun but the bulky construction could mean it’s a shorter assault weapon.
For reference, check if you can identify which type of weapons these are http://img07.deviantart.net/25ec/i/2014/128/5/d/future_gun_concept_silhouettes_2014_by_andyalford-d7hm3b1.jpg
These are assault weapons and you probably see why http://2.bp.blogspot.com/-HTz75_Sj0GI/TxsJhmq6ntI/AAAAAAAAAd0/RkBO5lQcfi0/s1600/vapen%2C%2Bwip1.jpg
I don’t like the design without a trigger guard. Yours, and some of the designs in the first reference lack that. If it has a conventional trigger, the silhouette is stronger with some kind of protection for it. A conventional trigger without the guard would also be quite stupid design because such a simple thing can make the gun safer and easier to holster.
The grip and the trigger also suggest the weapon is for humans or aliens with human-like arms and hands. The way the weapon is held can dictate many design decisions, at least if it’s based on reality like successful designs of any kind usually are.
That doesn’t mean it has to be based on existing/real gun designs, just that the aspects of it make anatomical sense whatever creature uses it. Clear type when us humans see it gives it enough familiarity to be successful: handguns are small and short, assault weapons have heavier structure and more supports, (sniper) rifles are long and there is a scope on top.
Sure it’s fiction and an accuracy weapon might not need a scope, or a pocket gun could be more powerful than larger ones but you wouldn’t assume that. A pocket size rocket launcher would be quite practical thing to have but familiarity is more important in entertainment context when the viewers have to use their own judgement about its function. https://www.youtube.com/watch?v=fTqxFIpc1j4