Model created in 3D Studio Max 2009 and converted in multiple formats. All formats include materials and texture maps. The Max format uses mental ray materials and render. There's no need for a third party plugin or anything else, just drop your model in the scene and hit render.
The turret is a separate object and may be rotated at will.
The barrel is also a separate object correctly linked to the turret, so the elevation is easy to change.
Real scale object.
The AS-90 Artillery System for the 1990s is a lightly-armoured self-propelled artillery piece used by the British Army. It was first delivered in 1993. The AS90 Braveheart is a 155mm self-propelled howitzer. The AS90 was deployed in support of Operation Iraqi Freedom in March 2003, and other military scenes.