damn this is much better than my first model. You're definitely on the path to gun model divinity here.
Also, just for the future, I suggest you post these in the creativity section. There are a lot of people who love to critique and share creative ideas there, and you'd definitely get more fans and probably even people willing to help you if you post these here. For now though, don't worry about it.
I'm not one to force modeling styles upon other people, but here's a little tip: when modeling guns, it's always good to start with a flat 2d image off the internet and break it up into sections. It looks like that's what you're doing here, but just in case its a good place to start.