The Marlin rapid cannon is a Italian manufactured close in weapon system made by Oto Melara, which is now Leonardo-Finmeccanica.
The model is created in 3ds Max 2016, and rendered in V-Ray 3.4. I work as close to real world scale as i can (in cm). I build my models based on references found on internet. Blueprints, photos and data found on internet.
The materials are V-ray materials with V-ray triplanar textures and dirt materials. I have built most of my models with the same multi-material setup for easy adjustment. If you are in the real-time game engine scene you maybe will need to do some unwrapping work. For now, i will leave the models as they are.
For modelling i like to create hard surface models without sub-d options. I have subdivided the models before cutting out the doors or other shapes. My opinion is that this will keep polycount relatively low. The edges are bevelled in.
The shown renders are created with HDRI lighting, which is excluded from the scenes. The images are without Photoshop post processing, except cutting out the background an giving them a simple drop shadow.
The model is divided in Base, turret, and gun for easy positioning. The pivots and hierarchy are setup correctly.