James K brought up some ooints I was going to make. Even if you overcome the hurdles and requirements for getting a FFL - you have a lot of things to think about in terms of state and local requirements.
What state are you looking at? Do some research on the internet in regards to what they require to have a business. You will be responsible for business registration, filing state forms, sales tax license and monthly forms, etc., etc., etc.
While it is noble to want to have a business and follow your dreams . . . the reality of it is that it is a uphill struggle to start a business, let alone make enough to stay in business. While you could rent a location . . . remember that the rent is due each and every month and you have produce enough income and profit to meet those needs - they don't go away and on top of it, you have to make enough for your own private expenses.
I have had a commercial building for sale since shortly after the "big dive" in the economy. Fortunately, I own it free and clear but I still have monthly expenses of insurance, water and sewer, electricity and maintenance. Right now, in our area, the few banks that are giving commercial loans for purchase of real estate require a 40% down payment before they will even talk to you.
As has been noted . . . . a lot of gun sellers who have shops are barely scraping by. I love this country but the way things have gone, it certainly doesn't promote anyone to go in to business - there are way too many rules and regulations - many of them showing no common sense - but that is another issue.
I applaud your ambition . . . but I would be remiss if I didn't suggest that you go in to a different line of work . . . one that provides for a good and steady income that has a promising future where you will be employed for years to come . . . . and follow your interests in guns, shooting and hunting on a recreational basis.
Welcome to the board by the way and my very best to you in whatever path your feet lead you down!