I'll look into Gearbox later, I'm not sure what the requirements are for that sort of compatibility.
As for how he holds his pistol, that's not gangsta style, it's more tacticool, and it was a result of how HORRIBLE the gun looks when fully centered, case in point:
The only other thing I could have done to rectify this would be to do significant changes to the weapon model, and this was meant to be a more relaxed project to blow off steam. So I went for tilting the gun instead.