Re: Carry paperwork with NFA weapon??
IMHO, anyone firing an M14 in the FA mode at many ranges is, at best, irresponsible. There are some selective fire rifles (M16 is one) that can be fired FA with reasonable control, but the M14 isn't one of them, which is one of the reasons the Army issued them with the selector switch lock. At some ranges, firing over or past the backstop could endanger persons or property, and an M14 will climb due to recoil and stock shape.
This is a case where I would have the papers along. I know of a case where a man had to "assist the police" for several hours because he was spotted with an M1A with a dummy selector, so a true selective fire rifle could result in a similar situation if the owner has no papers.