In all likelyhood, that was taken directly from the original packing slip. The carbine numbers would have been listed in the order in which they were put into the original shipping case. Since they were all issued carbines, no particular order would have been followed, just grab one, list the number and stick it in the case. If the numbers were painted on the outside of the case, they would appear in the same order as the list. They weren't consecutively numbered anyway.