A good gun range bag should be large enough to fit all of your guns, ammunition, hearing protection, cleaning supplies, and other shooting accessories. It should also be durable and water-resistant, and have multiple compartments for easy organization.
Look for a bag with adjustable straps for comfortable carrying, and look for a bag with a load-bearing frame for extra support. It should also have extra padding to protect your firearms and accessories, and it should be easy to open and close. Finally, look for a bag with a bright, recognizable color so that it can easily be spotted in a crowded range.