Leave weapons and ammo in your vehicle unless you're carrying a hand gun on your belt. Seek out an Instructor to check in and find out how he or she wants to stage equipment. Most of the time, you will be asked to place your unloaded weapons on a loading table, facing away from the range, slides open with chamber facing up. At that point, no one is permitted on the muzzle side of the tables. The Instructor will inspect weapons if necessary and tell you what the next procedures are.
At no time are loaded long guns taken out of a vehicle. You should not even arrive at the range with any loaded rifle or shotgun (it is against NH law to travel with a loaded rifle or shotgun in a vehicle).
Remember that there are other people at the range with you, and act accordingly when removing weapons from or placing them back into your vehicle--ensure they are on safe, finger straight and off the trigger, and pointed in a safe direction.