I'll second the "streamlined" approach. Trauma medicine can best me summed up in one word: SLOWER.

If the patient is bleeding fast, you want them to bleed slower.
If the patient is thrashing around, you want them to move slower.
If the patient is panicing you want their mind to go slower.

The "fast" part of trauma medicine is all about how fast you can slow down the problem.

And that requires only a small amount of gear.

Look, the fire company just bought a used ambulance, which was used as a BLS (basic Life Support) rig. This was an AMBULANCE, and they gave it to us fully stocked, and while there was lots of stuff on board, there was lots and lots of the same basic stuff - a cabinet full of gauze in various sizes, another cabinet full of sterile water, some bandages, some ointments (numbing cremes, mostly), O2, some backboards, a few BP cuffs and stethoscopes, lots of gloves, instant icepacks, some goggles and masks, a gurney, some splints and, well, that was about it.

And it just so happened that the night we got the ambulance we were also doing our O2 delivery certification, and we had a paramedic with 20 years experience there, and I asked him to help me make up a couple of jump bags with all that handy stuff on the ambulance. The kit he packed for me was basically a collection gauze, gloves, bandages, tape, a BP Cuff & Stethescope, N95 mask and a penlight. That's it. He said that we could add a "boo boo" kit to that (bandaids, neosporin,rash ointment) but that's not really what a trauma kit is all about.

So back to the civillian use of the medic kit described. While I've seen a crainial GSW up close, I've not a lot of experience with them. The last trauma victim I saw, which was yesterday, was already dead, but before that, we had a pediatric with a compound fracture to the femur piercing the skin, and in that case all we needed was plenty of packing and a stong stomach as the medics attached the kid to the gurney. It was just a stop the bleeding job, as are most traumas.

You don't need much to do that.