Couple of different FFLS. An 01 DEALER FFL covers modern arms, but you must be IN THE BUSINESS to have one. Means business premises, zoned for business, sales tax ID #, business license etc etc etc. An 01 will NOT be issued for "personal use".
The other is an 03 Collector of Curio & Relics FFL (known as a C&R). This is for people that DO NOT intend to "engage in the business" of buying and selling firearms. Covers firearms that are 50 yrs old or older, OR- have been designated as C&Rs by the ATF without regard to age- as in ALL Winchester 88s, ALL Colt Woodsman pistols, etc. One page app, $30, good for 3 years, simple record keeping. DOES NOT COVER MODERN ARMS unless they are on the ATF C&R list. Your STATE may have additional laws that can be stricter, but not more lenient.
Most fun you can have for 30 bucks without catching something.
What we have here is... failure- to communicate.