I bought 3 boxes of old Remington Kleanbore 160 grain Mannlicher-Schoenauer cartridges at a garage sale on Saturday. THe boxes are marked 160 garin and for use in the 1903 rifle. One box is all soft point copper jacket with a headstamp of 6.5 m/m. One box is soft point copper jacket with a headstamp of 6.7 One box has about 10 shells that are headstamped 6.5 x 54 and are softpoints with steel jackets. They are definitely steel. What's with the steel jackets?