My last order from RST was a mixed case, had them include some paper case shells. Most of the time when someone writes or talks about a classic scent associated with hunting or shooting it's Hoppes #9. But for me nothing is as evocative of the past days of hunting as the scent of paper shells.
Other scents that come to mind are Barbour jackets, puppy breath, moss, and woodsmoke & Bourbon. Fishing scents would include 2 cycle exhaust and the mosquito dope we used back before deet. [can't remember the name of it]
Anyone care to add to the list?