I'd say yes and no.
If it is original, FA and unregistered cannot be made legal.
If it is converted illegally, maybe. Remove the illegal parts, replace with legal parts. Converted back to SA.
If "no papers" means "never had any", stay away. There are ways to find out if it is in the registry and has papers.
Some folks don't know what they have.
Not saying get involved, but you can check your options.
Dave
TRW never made a semi-auto M14. They were a government contractor and only made M14's for the military.