Wow, you guys have really covered most everything. Here's a couple more:
1) Arms experts - you work at Butterfield & Butterfield and do appraisals for the auctioneers. You may even show up on the Antiques Road Show. Don't forget to say, "Hi Mom & Dad!"
2) Museum Curator - you luck out and become the curator at Springfield Armory National Historic Site, or the Smithsonian, the National Firearms Museums (NRA) or any of the other gun museums in the country
3) Museum Objects Conservator - you luck and and play with the guns and get paid to do it.
4) Apprentice - Along with 500 other applicants, you apply for that $15 an hour job to be a firearms apprentice at Colonial Williamsburg. After about 5 years, you'll know how to make a barrel from a bar of steel and how to rifle it, you'll know how to forge a lock, cast the buttplate, triggerguard, sideplate, or cold form the buttplate, make thimbles (pipes), stock, wiper (ramrod), engrave, relief carve and do wire inlay. I'd like to be an apprentice after I retire.
5) Park Ranger - As an "interpreter" you run around and give talks on guns and shoot them during your demonstration. Met a lady who does that as a Park Ranger at the George Rogers Clark Memorial in Vincennes, IN. She knew her history. Also knew a Lt. in the Park Police who use to do the Civil War demo with a mortar (18 years old at the time). He & his buddies used 1 1b of powder instead of the ounce & a half. It launched the mortar ball out of sight.
They formed a skirmish line and marched out about a mile before they found it - happily without a car or person beneath it. Got a royal chewing for that stunt.
6) Become a politico.
You wave guns in the public's face and tell them how you can kill 30 people in less than a minute. Fineswine and Wille Brown both did that before they got some of our black guns banned.