Definitely an interesting looking gun!
I agree that some of your edges are way too sharp, in the reference pictures the areas around the front handle and the grip are a lot softer. Conversely, the curvature on the rear handle thing behind the grip is a little too soft in your model. There are also a few bits and bobs missing yet, but I'm sure you're aware of that..
Over all your renders make it kind of hard to make out more detail - very good first effort though, if you're new to modeling!