The Lahti L-39 is a Finnish 20 mm anti-tank rifle used during the Second World War. It had excellent accuracy, penetration and range, but its size made transportation difficult. It was nicknamed "Norsupyssy" ("Elephant Gun"), and as tanks developed armour too thick for the Lahti to penetrate its uses switched to long range sniping, tank harassment and with the L-39/44 fully automatic variant, an improvised anti-aircraft weapon."
This a 3D model made mainly as personal practice. I used Rhino5 for modelling, and Maxwell Renderer for rendering. The L-39 model is not intended as a 100% accurate 3d replica of the real-life rifle, so gun-nuts and enthusiasts, please don't bother with picking the details.