Now that we have the dimensions, it is most likely the 1839 carbine cartridge box but should have an inner flap cover which may be missing as well as the small oval pieces ("ears") of leather that were sewn to the cover to keep rain out. I have one just like that and they were made without the implement pouch. They were meant to accompany the Hall carbine. They did not have copper rivets on the belt loops and none on the cover to secure the leather latch tab that goes over the brass finial. There were several other carbines of this early period that this may have been used for besides the Hall carbine: Sharps, Symmes and Perry carbines. (Source: Civil War Cartridge Boxes of the Union Infantryman by Paul D. Johnson)