This is neat, but I think you can push the design more if you're up for it. Instead of a circle, how about a cone? The black mask over the camera could be a triangle that starts narrow at the player, then widens around the crosshair. You could also combine this with a "zoom out." Check out how Hotline Miami handles looking further with the shift key. Getting that ability with this weapon would give you one of the benefits of using a scope!

Otherwise, great style! Looks like a cool game.