One can typically gauge someone's knowledge and experience directly on their opinion of tampons as emergency medical devices.
Care to elaborate on how all of your LEO experience makes you qualified to critique someone's medical advice? I have over 20 years of career EMS and many as a SWAT medic which tells me otherwise. But I have a college degree, a license to practice this stuff and actually make my living providing emergency care. The OP asked a basic question so I gave a basic and cheap to procure answer that is very effective!
I have treated an absolute ass load of GSW's and unless their is arterial involvement they don't bleed for shcitt. If their is Only moderate bleeding you typically just need a packing device and pressure bandage I.e Coban or Israeli dressing. In the case of significant arterial involvement, pneumothorax, hemopneumothorax, suspected abdominal organ (main concern is liver and spleen) injury or head injury concerns with the shooting then your probably going to need a lot more then a single blow out kit to save a life.
The fact is the OP asked about a kit for the range which to me means fire/EMS is minutes away. In that scenario a bleed kit with material to pack wounds, Israeli splint or Coban for pressure and a triangular bandage to immobilize and a possibly simple CAT or Sofft tourniquet is likely enough. He didn't ask about a kit for hunting miles from the road or about a blow out kit like we both carry for entering austere environments such as active shooter events where EMS won't enter until the scene is secured. Im quite sure that the blow out kits that you, Blue and myself and others here carry are all very similar in their contents but as we are using them in possibly austere environments and we have training to use that equipment.
For small extremity wounds from handguns a tampon packed into the wound and covered with a pressure bandage with significant force to tamponade the bleeding is typically more then sufficient. Larger caliber holes can indeed take a lot of packing but in a extreme case, people are usually always wearing a shirt at the range, hell I always have clean terry towels in a ziplock in my range bag so packing material can be improvised as anyone in need of that level of packing has bigger concerns then a possible infection risk.
Outside of a freak accident I have a hard time imagining a Hunter or Causal shooter having to deal with sucking chest wounds . Abdominal and extremity injuries will probably be 95% of what they will see. Therefore most guys aren't going to go out and purchase adequate quantities of legit bandaging supplies that we both have access to. This is even more so when they realize a lot of this stuff has expiration dates so it needs to be monitored and replaced.
Chest seals are damn good items to have for sure and I have both Hyfin (vented) and Halo (both vented and invented) in my first aid kit. But again let's be honest quality chest seals aren't cheap and don't accomplish a single thing that can't be done with a chunk of plastic wrappet or cellophane and taping to the chest leaving one small corner untaped to act as a valve. in a austere situation I will take the speed of a real chest seal, but again that doesn't mean the same thing can't be done cheaper with materials already on hand.
Fullauto01 mentioned trauma shears and I keep a pair in each of my first aid kit but typically only use them for cutting bandages. For exposing injuries or quick cutting of seat belts, clothes, web nylon etc the Benchmade Rescue Hook is without peer. Cheap at under $30 and has countless uses.
My own blow out kit the gist is 2 Hyfin vented seals, 3x compressed guaze, 3 occlusive dressings, a roll of Vet Wrap (Coban), 3 sizes of NPA's, a Softt tourniquet, an Israeli bandage, a roll of medical tape and a Benchmade rescue hook. All of this goes into about a 6"x8"x3" Nylon pouch. All of these items definitely have their places in medical care but all require some understanding of the device and the how/when to use it or they are at best ineffective and at worst more harmful to the patient
A quick note about clotting powders, gauze and sponges, a lot of this shcitt is nasty!!! Much of it has an exothermic reaction when it hits blood which causes burns, and it has to be surgically removed. In a true life or death situation with arterial bleeding it can be a lifesaver but it isn't the end all be all.
It's quite possible that I misread the OP's wants/needs but it took it as he wanted a basic first aid kit with a few simple ad one for gsw. If we are discussing commercial blowout kits (as most of these medical supplies are sold in bulk) there are many good ones on the market but all could use some tweaking. I recommend the one from Itak Medical with atleast some extra Coban, petroleum gauze and compressed gauze added.