Most of the Mosin-Nagants on the market today, especially those that are being sold with bayonets and standard issued Russian ammo pouches are old stocks from former Soviet bloc countries that have been recently released for sale. These rifles have been fully re-arsenaled and have generally been sitting in cosmoline for the past 50-60 years just waiting for a collector to own one. During that re-arsenaling, the rifle would have been reblued and any repairs made to the stock or even a full replacement of the stock (which would account for the post war stock). Here's a great site for info on Nagants:
http://7.62x54r.net/