But if your grandfather brought back an M1 rifle or carbine or GI pistol, he stole it, and took a lot of risk.
yes, and sometimes, no. The M1 carbine does have the reputation as being the most stolen US rifle, mostly because it was the first US rifle that could easily be fit inside a duffel bag (without creating a noticeable lump...)
I have known a lot of vets, WWI, WWII, Korea, Vietnam, and now, some from the eastern sandboxes. Each one tells a different tale, about what, when, where, and why things could be brought back, legally.
Several different WWII vets have told me their experiences, and it basically depended on where you came back, and what time to day it was when you were processed (meaning who was on duty to process you out), when it came to how thorough they were about things.
More than one I have known was offered to buy their arms, and some did. And some still have paperwork to prove it. Not all the guns they brought back were "stolen" from the govt, but many were.
One friend is a perfect example. He was a Signals Sgt, finished the war in the Aleutians. When he outprocessed, he bought his .45 (and has papers for it). He had been given a carbine too, which he also kept. When he asked about buying it too, the Sgt looked at his paperwork and told him "You don't have a carbine." When he tried to explain that he did, he says the Sgt looked him in the eye, and repeated, with emphasis, "You don't have a carbine!". So it stayed in his duffelbag....
He knew it was "stolen", and for many years kept it in a closet, hidden, even from his family. His pistol was openly owned.
While I know lots and lots of guns were "stolen" from the govt after the war, I have never heard of the govt expending any energy trying to find them, or prosecute anyone for having one. (those who took case lots of guns were a different matter).
I can see where, the general belief that there would be trouble kept a lot of carbines "in the closet" for a long time, so there was little demand for new factory sporting ammo, especially with all the surplus stuff around.
That does explain a lot.