I belong to a private outdoor club. What you bring is what you use out there. You leave something at home or something breaks, you're screwed.
IF YOU DO NOT BELOW TO AN OUTDOOR RANGE, YOU NEED NOT READ ANY FURTHER.
Most range stuff I leave in my vehicle because it's a lot of work to load and unload.
Arntzen AR-500 steel (IDPA and Standard round targets)
IDPA Cardboard targets
NRA D-1 targets
Target stand (4 2x2s)
Being in an outdoor range, you become your own technical support for sighting your equipment, fixing targets, hanging targets, equipment failure, etc. Last thing I need after driving 24 minutes it to forget to bring something. Stapler and spare staples is a showstopper for me, if I don't have them. I always have my steel targets but if a joint on the stand, or the bolt that holds the target fails, it makes for a failed journey.
Sights can be off, particularly with ammo brand changes, despite same bullet grain weight. I never understand the concept of fixed sights, as point of impact changes for different loads from my experience. My friend has a beautiful PC S&W 629 with rear channel sights.
Universal Sight Pusher tool, Glock Front sight tool
stapler, spare staples
Trigger weight gauge
Toolkit with screwdrivers, torx screwdriver, punch
1911 multitool with pliers
AR-15 Multitool with knife
Spare CR2032 batteries
Green Laser boresight tool: Green is visible out to 25 yards
PACT Club timer: It is a way to track progress
Spare nuts, bolts, washers for my Arntzen targets
Adjustable wrenches for my Arntzen target stand
Upula universal magazine reloaders for pistol, AK, AR: Saves the thumbs, particularly with my volume.
Ruger magazine speedloader
flashlight (no lights in the woods, here)
Laser rangefinder, spare laser rangefinder
Rubber mallet (field strip my Mark II Ruger)
SPARE COMPARTMENT: Always have a backup plan.
Electronic hearing protection
Spare electronic hearing protection: because even though you tell a guest they need eyes and ears, some knucklehead doesn't.
Foam hearing protection
Spare box of Staples
AMMO BOX (50 cal size): Because If you forget your ammo, you're screwed.
Spare ammunition in 223/5.56, 300 AAC, 22 LR, 357 Magnum, 45 ACP
I just clean the Bore, feed ramp and slide after each shooting.
I don't always bring my Lead sled. It is helpful for sighting in as it takes out human error.
Pistol rest. Useful for load work ups.
Chronograph. How will you determine your effective range or distance, or even bullet drops without one? I use it in conjunction with ballistics apps on the iPhone. That's how I am able to shoot my handguns beyond the usual self defense range, for fun.