Thanks for the info. I didn’t know that about the bore size.
I had a Chinese carbine and it locked up after every shot. I would have to take a wooden club and hammer the bolt open. I gave it to a guy who later told me he loved it. I now wonder if I got a bad batch of ammo.
Also had a really long one which had the hexagonal receiver. It had so many markings on it that I suspect it had been rebuilt at least once. I liked that one OK but sold it along with a whole lot of other guns while in grad school. Simply had to have the money to stay in school.
That's one possibility. I had a pal with an M44 carbine that gave at its best around 14-inch groups at a 100 meters, using various surplus ammo. I tried a diet of my brass-cased reloads, and it settled right in around 4-5 inches, and a little load development knocked an inch and a half off that.