It seems to me, that a person either has a trauma bag or doesn't. Those that have one, hopefully know how to use it, and have it in the car all the time. There are a lot more dangerous places than a gun range.
I have one in my work vehicle. It's in my carport. My range is just outside my yard gate. Does that count?
In 1997, I had a serious accident at my shooting bench. I was shooting alone and walked the 40 yards to the back door. I might have been able to utilize a trauma kit alone but not likely. Had I been further from assistance, I very likely would have bled to death. There is some merit to having medical supplies available IF someone is there who knows how to use the kit.
Even considering my personal experience, I think you're 1000 times more likely to need such an emergency kit due to a vehicle accident than a shooting accident.
The local clubs I belong to all have a traditional first aid kit at each range, not a trauma bag (as an EMS/EMT would carry).
I believe most folks, including myself, would not know what to do with many of the trauma kit supplies.
At club shooting events we assign a 911 caller, and if one is present, an EMT to lead any medical situations until more help can arrive. Knowing who will do what in an emergency eliminates much of the normal initial confusion.
True "trauma bags" have things most folks aren't allowed to have. Primarily IV solutions and drugs. So what most of us have are large well stocked "first aid" kits. Although I do no one fellow who has an AED in his. I seem to recall it cost less that $200.
Doing what I did all those years ago, and more or less keeping up, my first aid kit in each vehicle is in a medium sized duffle and is just about filled to the brim. A list would go on for a bit, but basically if you are broke, bent, burnt, abraded, incised, etc. I will have most things I would need to deal with it. I don't carry a back board, but you can fashion those out of lots of stuff.
Now here's something I know most folks won't have. I have a bag with climbing stuff. I learned to use it back then and did that type of stuff for entertainment for years. I may not be as good as I once was, but I'm still as good once as I ever was (or at least I think). Climbing stuff has uses other than climbing but if you do need to get to someone who's stuck either above or below you it's pretty darned near impossible without it.
One other thing about first aid kits, and it doesn't matter whether it's a cheapy from the local supermarket of a full on one you put together yourself (there are now some on the market that are pretty good, but costly). You have to maintain them. Things expire. If they are kept in a vehicle the heat and cold can take their toll. It would really suck to need a particular item and find it spoiled.
Since my motocross days......a long time ago.......my kit has contained sanitary napkins and vet-wrap. They make a great compression bandage, are inexpensive and easy to resupply. I also keep the number to the local "dust-off" in my phone...... 8)
WE carry them in all the pickups. Too many guys, myself included hurt seriously over the years out on the desert and the ranch. After spending a fun filled 3 days with a compound fracture at Indian Crossing on the Owyhee River and being Life Flighted, again, I sat down with my primary at the VA.
EVERYBODY on the ranch has a Red Cross Advanced First Aide Card and several either were hired after being previously employed as rural EMTS or in two cases, sent for training.
So, drugs, blood clotter, Morphine Surettes, Air splints for both arms and legs, suture kits and all the rest. Each year in the springwe inspect all of the kits and update supplies and outdated drugs.
IF you get a message to either Boise or the Air Base in Mountain home you re still talking a 2+ hour flight to get here and at least 2 back.. The first thing my mother did when I inherited the the ranch was to purchase Life Time Life Flight for the Ranch. In the 22 years I've owned the ranch they have responded 17 times. Money well spent.
I catch ......... from the Cousins frequently because NOBODY works alone out here. They view it as an unnecessary expense. Okay one exception to the rule, your's truly. I AM prettyy good about telling people where I'm going and when I should be back. The down side is that as a general rule nobody starts looking for 3 days. It's usually broken vehicles and if somebody went looking every time somebody was a day or two overdu we' never get any work done. STUFF happens. I've been flown out 5 times. ;-(
Worst was an adventure looking for a lost pup and I told the wife I could be out for as long as a week to 10 days till I found her. So, I spent 7 days and 6 nights up under a rim with a broken/tweaked back. I did one smart thing and that was took my ruck with me with water, space blanket, survival food. matches etc AND my meds.
I'm "retiring" again. The new house is off grid BUT it is a 2 hour drive to town, not a 5 hour drive.