Driven by the need to inflict mortal wounds on my foes, I’m kitbashing a tactical gunner lugging a heavy bolter to cover.
The heavy weapons specialization allows him to fire after moving, so the sprinting pose seems appropriate. Plus the ultra-static, unnatural poses of most GW heavy weapons loadouts are… well, they’re not very cool. As usual, the positioning of the shoulder pads, in particular, will help create an impression of rotation in the torso and cant in the spine, which really improves the dynamism of tactical marines.