Found a little more info about the model you bought, thanks to an AWESOME resource book "The Mosin-Nagant Rifle" by Lapin:
The large number of M1891s available to the Finns encouraged them to experiment with various methods of salvaging otherwise unusable barrels. Capitalizing on Italian success with the Salerno process of barrel relining (sleeving the barrel and recutting the rifling), the Finns rebored about 13000 M1891 barrels at the government's Arsenal No. 1 (Asevarikko-1, or AVK-1) at Helsinki during 1925-27. This so called "P" series, from Suomessa putkit tehttu ("[rifle] bores made in Finland"), the rifles being identifiable by the capital P on the chamber followed by a dash and the numerals 25, 26, or 27 designating the year. As part of the "P" process old markings were removed and the barrels renumbered. Those barrels not used at the time were placed in storage and used a decade and a half later as part of the World War II production of the m/91.
Pretty cool little curio you have there...