This is almost complete in my honest opinion.
I still need some “focused” critisizem,
go ahead.
Modelling, materials & texturing seem very solid, very nice indeed. The scene need work though. I get what you’re going for, storywise, but it’s not really logical. Is the case and plans on the floor and, if so, why? If it’s in it’s planning stages, why are there casing and not bullets - and what hitman spreads his casings around? You need to get the scene logical. 
But from a technical standpoint it’s very nice work indeed.
(makes me think of James Cameron. When he checks out a modellers work, he randomly asks questions about the details, like ‘So what does that handle do, what is behind that hatch’ a.s.o… Everything’s supposed to have a reason. :D)
Errm, to be honest, I expected these types of comments and thats what I wanted to get as critisizm, the gun is the main focal point (clearly) and I just modeled some quick background junk to make it more gun related.
I need a back story to work with and I’d love to hear any suggestions you might have 
Hehe, but you kinda planted a story, right? The flowchart of the ‘mark’, city maps where you’d probably mark his house, route, lover a.s.o… So you do have an idea, kinda… I’d just place it on a table or a hotel bed, just an enviroment fitting a hitman…
But as my comment on James Cameron, that’s kinda how I work (at least when applicable) - it’s always the ‘why’ that makes the story. 
Also, viewing it again, kinda reminds me of the restaurant scene in ‘La Femme Nikita’, the wooden box with a Desert Eagle in it that she gets as a ‘welcome out present’ together with -“Behind you, there’s three men, two are security and one is a business man…” ;D
Ill work on it, more?