1. A firearm that is one the list published by BATFE - OR
2. Firearm that THE GUN IN QUESTION is 50 yrs old or older- not the model, the individual gun. a 50 yr old Marlin 39A= C&R. 49 year old marlin 39A= NOT a C&R. Gun should be in original config (not sporterized, etc) OR
3. Curator of museum applies to BATF for C&R status for a specific firearm- Chas Lindberg's pistol that flew the Atlantic with him, .45 that belonged to last President of Cuba, etc. Scarcest of the 3.
Advantage of having a C&R FFL- I can collect anywhere in the country- live in VA, go to show in Colorado, my FFL is good there FOR C&R GUNS ONLY. And when I find a gun I like, maybe for sale by a dealer in Washington, we agree on price, I send him $$ and a copy of my C&R 03 FFL, he puts rifle in mail to me. My license is $30, good for 3 years, no need to pay a dealer to receive guns for me. Except for modern guns.
Not limited to milsurps- altho many milsurps ARE C&R. Does not apply to barreled actions- complete guns only. Most fun you can have for $30 without catching something embarrassing.