Actually, most of those five (if not all) were used since they show acceptance stamps by the U.S. government placed at the time they left the factories as complete new M1Carbines. Some have acceptance stamps applied later as "rebuilds" at various arsenals as noted by Wayne. I think I see both types of barrel band imprints in the picture that shows the five in the box. Possibly, they would have been OK for use on guard duty, such as SAC bases, etc. but the early stocks without the "pot belly" are already pretty weak before having the bridge milled out. I've got an NPM stock with a similar stain, but likely from something other than blood. - Bob