The SA in the rounded corner box stands for
Suomen Armeija - "Finnish Army".
The mark behind the "1934" is Cyrillic letter (insert a one armed 'T' with serifs)
geh. It's the abbreviation for "God". Thus the barrel was made "In the year of our Lord 1934."
The year the receiver was made will be stamped on the bottom side of the receiver tang, behind the hole. If it's not there then the Finns removed it when they serviced the rifle.
I got this out of the "For Collectors Only" book
The Mosin-Nagant Rifle by Terence W. Lapin. A pretty imformative book for $20.
Couldn't find anything about the other markings. There are some excellent MN websites around too. Can't recall the names though.
Cool find! How's the bore? I bought two and their both dark and rough, but fun as all get out to blast with.