Game Assets & Mostly Guns

I’ve been enjoying making low poly guns and using Substance Painter, so I figured I’d share some of the renders with the community. Most of my guns are for sale on Turbosquid. Please post your comments and critiques, I’d like to know what I’m doing right, as well as what I’m doing wrong. My goal is to be able to create game ready models that could eventually lead to me getting a job in the game industry. My main focus is the modeling portion I find the texturing is pretty easy in Substance Painter.

A few renders of the AK-47

Some renders of the FN-FAL, this model, along with the AK are for sale on Turbosquid

M40A1 Render

Thompson M1A1 render

Look nice.
You can describe the development process models for the engine, ie as I understand it, first, create a hi poly model and then low poly is created? also heard that you can or even should apply the normal map instead of geometry? can enlighten these issues or give some resource?
Thank you.