legal or not

Question
a coworker was sent home from a public shooting range because he showed up with a sawed off stevens model #530a 16 ga side by side..the gun was made in 1951 (manufacturer code letter "c") and never had a serial#...barrel was about 12 inches and overall length with stock was about 22 inches..when his grandfather passed away his step-grandmother gave it to him...it was the grandfather's "critter gun" as she called it...without NFA paperwork the range officer (AS DID I) clearly saw it as not legal...my coworker said it was legal as his grandfather cut it down in the late 1950's... he said it is "GRANDFATHERED" (no pun intended) who is right

Answer
Hello Rod,

You are absolutely correct. Your coworker could easily be sitting in jail right now for possessing an unregistered NFA firearm. I am surprised the range did not call law enforcement.

Your coworker's 'critter gun' is a Short Barrel Shotgun (SBS) as it consists of a shotgun that has a barrel less than 18 inches in length and is subject to the National Firearm Act (NFA).

http://www.atf.gov/firearms/faq/national-firearms-act-short-barreled-rifles-shot

It does not matter that his grandfather converted the shotgun into a SBS in the 1950's as the NFA was enacted in 1934. Regardless of date, the NFA permits only manufacturers, makers, and importers to register firearms. Mere possessors may not register firearms. An unregistered NFA firearm is a contraband firearm, and it is unlawful to possess the weapon." [26 U.S.C. 5861(d)]

Violators may be fined not more than $250,000, and imprisoned not more than 10 years, or both. In addition, any vessel, vehicle or aircraft used to transport, conceal or possess an unregistered NFA firearm is subject to seizure and forfeiture, as is the weapon itself.
 
http://www.atf.gov/firearms/faq/national-firearms-act-firearms.html

I am not an attorney so I will not advise your coworker what to do. I can tell you the BATFE says to contact the nearest office for disposition of unregistered NFA firearms. The firearm will seized and destroyed. I have no idea if he will be arrested and prosecuted for possessing a contraband firearm.       

To find the nearest BATFE office:
http://www.atf.gov/contact/field/