Shortround6
Major General
The idea behind the .30 carbine was to give the "2nd line troops" something more effective than a pistol and yet something less cumbersome than a full sized rifle. Giving them Springfields does away with that "advantage". I would note that many european countries had used short barreled carbines for some 2nd line troops although 2nd line isn't quite an accurate description of artillerymen, engineers(sappers) and other combat troops who's primary job is NOT weilding a rifle. The Springfield and SMLE had been given 24in barrels instead of the near standard 29-31in barrels of "full" sized military rifles and the 16-20in barrels of the carbines in the hope that one medium rifle could cover both uses.
Armies had changed from before WW I to the 1930s with many more troops being used in "auxiliary" roles, like truck drivers and support weapon crews. What rifle do you give mortar men if you expect them to carry either mortar parts (barrel, baseplate,etc) or mortar shells on backs or in hands? I believe the "idea" was that the short light carbine would be kept readier to hand (like on the soldier) more often than kept in a rack or stacked in a group at some not so convenient distance from where the work was being done. The US had issued a considerable number of pistols and the idea was that .30 carbine would replace a number of those. Full size bolt action rifles weren't really going to replace pistols and were not going to really free up any large number of full sized M 1 rifles for front line troops.
What the Ordnance Dept thought and what troops did in the field were often different things.
Armies had changed from before WW I to the 1930s with many more troops being used in "auxiliary" roles, like truck drivers and support weapon crews. What rifle do you give mortar men if you expect them to carry either mortar parts (barrel, baseplate,etc) or mortar shells on backs or in hands? I believe the "idea" was that the short light carbine would be kept readier to hand (like on the soldier) more often than kept in a rack or stacked in a group at some not so convenient distance from where the work was being done. The US had issued a considerable number of pistols and the idea was that .30 carbine would replace a number of those. Full size bolt action rifles weren't really going to replace pistols and were not going to really free up any large number of full sized M 1 rifles for front line troops.
What the Ordnance Dept thought and what troops did in the field were often different things.