Is the shellack intact? If so, or at least "mostly" and theres cosmo, it probly "is" right outta the crate, but ask the sales man.....
In 1946 there was a general armaments refurbishment program in Russia, that lasted untill 1954.
All small arms were counted up, cataloged, refurbed, destroyed, given to new satalight countrys or finally packed away for WW III.
If its a refurb, it was checked for throat erosion, obvious bore damage, bad chambers, and rebarreled if in need, headspaced, firing pin protrusion set, extractor checked, wood repaired or replaced, reblued, the sights are brought to the Soviet point of impact, then it as smacked with inspector marks, a "refurb box" , then restamped or electropenciled #'s onto any replacement parts to have "matching" serial numbers, then shellack'd to protect the wood, cosmolined to protect the metal and stored for later wars that never called.
If has a square with a slash diagonally through it, it was refurrbished, and the box will be on the buttstock and on the chamber.
Clean it of cosmo, especcailly the chamber, I use gasoline and a good scrub, I mean a REAL GOOD SCRUB!!! in that chamber 'cause the cosmo can be in there ,dryed on shiney, but definitly there and give you trouble with "sticky Chamber" syndrom.......get that cosmo OUT!
Its a rimmed cartridge, they headspace on the thickness of the rim, not the chamber. Its never a problem with Mosins, ever.
What you need to watch is the fireing pin protrusion, if ever you remove the fireing pin, you will have to use the simple protrusion gauge on the side of your soviet issued Mosin Nagant Screw driver/pin gauge/wrench tool, in your Soviet issue cleaning kit.
Then go shoot it to your hearts delight.
Keep it clean and enjoy!