I'm glad to hear that med training and equipment is being disseminated throughout your guys' agencies.
The way its typically taught in military/LE is when tourniquet(s) fail to control bleeding, or a wound that cannot accept a tourniquet.
At least in an urban EMS setting, wound packing may be counterproductive for most situations. The trauma center is usually close enough that most GSWs can be treated with a gauze 4x4 or gloved hand...packing would waste time on scene, and also waste time for the trauma team. That whole team approach, thinking about the continuity of care thing. There was one particularly nasty chainsaw vs leg that was pretty big, so the guys packed it (I have no knowledge if it was properly packed). About 1 minute from hospital it turned into a code, and we all know how trauma codes turn out......