This seems to be one of your first models so i'll try to be a bit easy on you.

First off: If it's your first, do a WiP and see if people can give constructive criticism on it before release, see if anyone can help you get it better or if it's good to go.

Secondly: Consider holding the weapon yourself. It has a block grip, you wouldn't enjoy holding it, right? It's not comfortable and therefor not that good of a grip. Check out other weapons for references how a grip should look like (ex: M4a1, MP5, Glock 18) and use these to make a better grip.

Third: Learn about smoothing groups as your model is currently quite broken when it comes to these.

Fourth: Put a lot of time into where you can waste a lot of polys and where to not waste (some stuff are more seen than others, you would not spend 10k polys on a trigger, spend them wisely).

There's some effort put into this model, just not enough to make me download it.

Consider watching tutorials about modelling (millenia, who is a member here, released a great tutorial about modelling some time back), though you may not get into a great modeller just by watching them, you may learn some and improve your work in a way you might have not been able to without the knowledge some of them gives you.