The only 1942 Manual I have is a Technical Bulletin, not a field manual (TB 23-7-1) and it does not show any cartridge for the carbine except Ball M1. No mention is made of box quantity. My earliest Field Manual (FM) on this weapons is FM 23-7, dated 22 April 1944. This shows the 2nd Model rear sight that was adjustable for windage, even though few carbines so equipped made it to combat zones during the war, along with the earlier flip-type two-position sight. The bayonet and bayonet attachments are not shown, with doesn’t surprise me, since there is little evidence that any carbines so equipped were actually used in WWII… It shows carbine ammunition being packed in 50-round boxes, although it holds open the possiblity of other packaging (but probably referring to Grenade Blanks). The ammunition section includes Ball M1, Grenade Cartridge M6, Auxiliary Grenade Cartridge M7 (with a warning that they are to be used only in an emergency, not to be fired from the shoulder, and with instructions how to tunr the carbine to prevent stock breakage within a few rounds fired!), and tracer cartridge M16.
It is interesting that this manual was classified as “Restricted” even as late as April 1944.