Good job. Could you post some wires please?
What kind of animations do you plan?

In my opinion the one at the bottom middle is nearest to your reference. Looks good though.

Good start but the arms are misshapen.

Looks pretty nice but you have some edge loops which are unnecessary although they seem to be placed correctly.

Since this project isn't finished yet maybe someone could push it into the WIP forum.
The picture itself looks nice. Could you also post a non-wired (maybe rendered) picture ?
Thx...

Try to create the AO shader in a different way. For example:
1. Go to Windows->Rendering Editors->Hypershade
2. Create a Surface Shader
3. Go to Textures (left bar) and create mib_amb_occlusion...

Considering that you're a starter, your models are really good. You should think about some rendering improvements to show your models in a better way. If you have questions about some little...

Nice model! Could you post a wire?
Is this a laserpointer which is mounted at the top of the barrel?

Could you post a wire ? :)

Great textures. Btw: nice avatar XD