There is PBR low-poly gameready model of soviet anti-tank gun. The model was made according to my own design.

• Model information:
• 18878 tris and 10271 verts;
• . fbx, .obj, .blend formats;
• .png format of 4096x4096px textures (but you can decrease the resolution, which will cause to a decrease in quality);
• 7 PBR textures of general pipeline
• also textures for Unity and UE4

Unity and UE4 engines allow to use packed textures to optimize memory usage (for example, in UE4 textures, metallic map is packed in B channel of OcclusionRoughnessMetallic texture).

For any questions related to the model or problems using the UE4 and Unity textures, you can ask me.