What those other guys said. First you need at least a FFL for gunsmithing. BTDT. 2nd you definitely have to have some insurance. I carried a million bucks worth. It really wasn't enough. Been a few years back and it cost in the vicinity of 5 G's for the insurance. Third to get a FFL you need to have a business license and for a gunsmith not necessarily a store front but an out building or whatever. And Zoning for the business so that the FFL can be issued. All this is a PIA to get started with and then you have to have supplies parts some specialized tools(write offs my friend) and then you don't really want to make a big profit(yeah)..then you'll want to carry some reloading supplies and maybe reloaders and the next thing ya know ya got a business that takes an awful lot of time. My gun business almost put me out of the fishing and crabbing business. And come hunting season...they are always at your place. Believe me. For 15 yrs running on the night before deer and goose seasons I was in my shop till at least midnight. Now having said all that...HAVE FUN You'll learn a lot. OH and get 2 Books...Gunsmith Kinks and Gunsmith Kinks II. Lot to learn from those books and any other firearm assembly disassembly books will be needed. Oh and for good profits...learn how to rust blue. Don't need all that dangerous chemicals and pretty easy to do. When ya do it right it'll pop their eyes out and make 'em dig in their pockets
In 1990 I charged 200 bucks and up for a rust blue job.