Argh! Soooo close to being NR!
Early on you could have a flash hider installed/permanently and get around the restricted BS but that changed .Didn't matter if it was welded on.
It is my understanding that this is the firearm that caused the 18.5 inch rule. In 1969 these were common surplus and when they were drafting the legislation, 18.5 was chosen because all the M1 carbines would become restricted. At the time they were the scary rifle they wanted to ban.
I remember clearly that the rationale was that it was the Montreal bank robbers’ weapon of choice...
At one time pre-Allan Rock a flashhider could be welded on to lengthen the barrel. Not now.
18.5" is the law.