Was given this box as a gift this past Christmas. It is a bit out of my line but rather interesting (to me anyway). There are 46 rounds left in the box (they have no headstamp, just like the box says) and the grease is still in the box and has not been used. Made me wonder, does anyone specialize in tool cartridges? I have guesstimated this box to be circa 1950’s. Can anyone narrow this down?