I bought a 49 at auction and looked at the website to see if the serial numbers were sans-serif. The S/N's shown are all sans-serif. Rifle serial number is ЮE 1217. ЮE 416 has only receiver sans-serif, ЮE 1217 has all shown S/N's sans-serif. Figure that one out. I should be getting this rifle next week.
https://bid.switzersauction.com/item.aspx?i=49739629
Interesting stuff. I've always assumed that sans serif 1's were the norm in early '49 and the transition happened midway through the production year with serif 1's appearing on some carbines having a mixture of sans serif and serif 1's until at the end of '49 production, all 1's were serif.
If this isn't the case then it may be that refurbished and restamped parts were exclusively given serif'd 1's and the sans serif 1s are exclusive to 1949 as sans serif 1's are not seen in any other year production as far as I know.
There are lots of Russian SKSs in that auction gives me the heebie jeebies man, lots of them. Some of those stock stamps and cartouches really scream that they were recently stamped to me...