This is a low poly model created in 3D Studio Max of a AKS-U74





The maps were made in Adobe Photoshop using the Highpoly model to bake the normal map and AO/Dirt maps.
Also plug-ins such as Xnormal were used for normal map details



The highpoly consists of subdivided geometry with edge loops to support hard edges.
It also has floating geometry for some of the detail that you can see on the sides as this is baked into the normal map and removed on the low poly model.