OK first off the MO stamping stands for "Ministerstvo Oborony", The Defense Ministry was established on March 15th, 1953, This was the result of a merger of the Military and Naval Ministries. The markings are found on M91/30, M38, M44, and M91/59 Mosin Nagants. Are they worth more? to some. The fact that it is a M38 makes it worth more off the bat. The Mosin carbines are very collectable at the moment. The M59 is another awesome rifle. They were for a while the best kept secret in the Mosin Nagant community. Once word got out about them however they were snapped up by collectors just like the M38's. I don't believe I've ever seen a M38 MO stamped rifle. I had my eye on a triple stamped MO M91/30 at Cabella's in Idaho, but they would not sell it to me because I was a CA resident.
“Americans have the right and advantage of being armed – unlike the citizens of other countries whose governments are afraid to trust the people with arms.” (James Madison, The Federalist Papers #46 at 243-244)