Well, Hello folks. I've been lurking here for some time, wondering what to make, but then it came to me that there are some obscure weapons of war that are known by only the thoroughest of gun enthusiasts. Therefore, as my first contribution to this forum, I present the reason why people think the SKS in 7.62x39mm was used in WW2: the SKS-31 battlerifle in 7.62x54mmR. Only a couple were ever made, but they still participated in the First Belarussian Front and the Battle of Berlin. It wasn't successful enough to keep the full-power three-line round in main service, but enough to be adapted first to 7.62x41, and then 7.62x39mm. And as they say, the rest is history.
To give credit where it's due, the main base of the weapon was, of course, Raspingleech's SKS. I also took some notes from the designs of Kiwi Imperialist, Scootia223 and others.
If there are any mistakes, please point them out to me.