Mosin–Nagant M91 Finnish

Finland acquired many Russian and Soviet Mosin Nagants by various means including capture and purchase.  Not all of them were stripped for parts and rebuilt with Finnish barrels, but were put back into service as they were, or with minor repairs and upgrades.  Sometimes the only means of identifying these rifles is by the Finnish markings, of which there are several.  The most common is the "boxed SA" mark which is an abbreviation of  Suomen Armeija (Finnish Army) and used as a property mark.  Another common mark is the "D" mark, usually found on the chamber, but sometimes on the rear sight base.  This indicates that the throat of the rifle was opened up to allow use of the Finnish D166 round which required more room for the larger ogive of the bullet.  If the rifle was used by the Civil Guard it will have an "S" followed by a number which indicates the Civil Gaurd district it was issued to.  If it has two Ss and a number that is an indication that it was an army rifle that was loaned to the Civil Guard.  Most Civil Guard rifles were transferred to the army when the Civil Guard was disbanded and also have the "boxed SA" mark.  "=S=" is the Civil Guard acceptance mark which sometimes accompanies the S number.  All the Civil Guard marks are less common than the army marks.  "41" is believed to indicate the year 1941, but it's exact meaning is unclear.  It possibly indicates repairs were made at that time.  A truly rare Finnish mark is "PUOLUSTUSLAITOS" meaning "Defense Department" which was only used for two months in 1942 before being replaced with the "boxed SA".  Another uncommon Finnish mark on Russian/Soviet Mosin Nagants is the "3600" pressure proof.   Apparently the Finns questioned the strength of these rifles and felt a need to proof them.  The vast majority of Finnish captured and purchased rifles were not re-proofed.  The pictures below show the various styles and typical locations of the marks