Nice Late M-39.
There were two separate manufacturer's of the M-39
SAKO manufactured alll parts ,barrels too, except the reciver for the Finn Civil Guards M-28/30 Mosin.
The Finn Armys plant at Valmet,(VTK) with "Tikka" Tikkakoskoi manufactured barrels.They made a type called the M-27
The Civil Guard and the Army decided to manufacture one model at both factorys, the M-39. By far the most excellent Mosin variation ever....
After WWII ,in compliance to Soviet peace terms, SAKO was sold to the Red Cross and started making other things, Valmet (VTK) did service work to existing military weapons, refurbishing what rifles need it.
In the past I've owned many Finns, and while the stocks and outter fitting could be burned, scarred, gouged and chuncked off, if the bre was in really good shape, and it worked, they kept it. I have never seen a Finn Mosin straight from the importer have a bad bore, ever, no matter what the outside looked like. They were only interested in accurate rifle.
"Sneak" rifle was a term an importer coined to explain the lack of manufacturer's markings, because the Russians had imposed strict arms limitations for their WWII peace negotiations. But its not true, in the 'sneak' sense...because in 1962 they adopted and began manufacture their own version of the AK-47, openly, with the Finns, again making a drop dead rugged design better...
The general idea Ive heard from Finn sources was that these rifles were built buy students in Finn military/manufacturers armorers schools, with every detail attended to untill they were target grade. Made up from parts and barrels that had not been assembled before the M-39 manufacture was discontinued.
Some have barrels made in Belgium (IIrc) and with a bit more nickel in the barrel that gives a nice "plumb' color for a finish, rather than blue.
I, personally consitter it the ultimate bolt action Arctic hunting/fighting rifle. Accurate as the get out, as long as good ammo and a good shooter do their job. With time and use, the action and the sling will break in and slide as smooth as can be
You have scored a Rifleman's rifle. get some quality ammo and a cleaning kit, a book on the type and time for shooting.....