Ok, here are a few crits.
The stock is rather off, the stock folds into the inside of the holder, which is attached to a pin pivot, letting it fold.
The holder itself is off too, take a look at the NBF album again, and get some good references for them.
There is more of a separation between the grip and the ammo slot too, they are bevelled inwards.
The rear receiver needs to be smoothed out aswell, looking a bit jagged right now.
There are some areas that need some control loops such as the trigger guard and the grip.
Smooth the text, and etrude it out more so that it comes out better on the bake.