I think it was THENAGANTMAN on youtube that said charcoal lighter fluid is the quickest in cleaning up Cosmoline. After watching a 45 minute vid by Nutnfancy on youtube, I'm ready for one myself! I also want the M1895 Nagant revolver. (NOT like the one in my avatar) I'l be applying for my C&R FFL so as to ease the $ pain.
The box with the slash on the butstock is the Ukrainian refurb stamp.
The other marks on the stocks are inspector or approval stamps. Most will be in Russian cyrillic alphabet.
The rifles in the order you have are.
#1 1929 Tula (most likely an updated Dragoon)
#2 1930 Tula
#3 1934 Tula
#4 1933 Izhevsk. The little r behind the 1933 stands for year.
All are pre war rifles.
If you remove the rifles from the stocks there should be a date stamped on the bottom of the tang. It will only be three numbers with the small r, and will not always be the same as the date on the barrel. or mad at the same factory. So, 929r would be 1929.
This is a 1920 Izhevsk built on a 1900 Tula resever.