Eddie,
A EFM is a Commercially built in the
USA Carbine by a company called Erma Firearms Manufacturing, in the early to mid 60's.
These are not related in any way to Erma Werke of
Germany.
Pictures of the Receiver and Serial number could help some of our research.
If you can get pictures of the Receivers' Top Front Ring and Rear, along with pictures of each side.
As far as investing in one, I'd pass and keep looking for a USGI M1 Carbine.
You can read 2 pages of information about the EFM Carbines here....... But please read both pages-
Ermas Firearms Manufacturing
You might find this interesting. The USA sent nearly 49,000 M1 Carbines to Mexico.
Maybe more, but this is all the records found so far. Research done by Jim Mock, who I call 'The Sleep Less One'.
Open this link and go about 1/2 way down the page:
The U.S. Caliber .30 Carbines - Slides
Eddie,
Please try to get close up detailed pictures of that EFM Receiver. Serial number 12 is the earliest I've ever read about.