The information obtained from rebuilt carbines is just as valuable as data obtained from original carbines. What is especially of value on rebuilt carbines is the serial number, size and type font, all the markings on the receiver as well as the barrel make and date. While the individual parts don't tell much about the carbine, since they were not on the carbine when it was assembled, what type they are and how they are marked is important. Also, the more accurate a datasheet is the more info can be obtained from it.