"Nothing useful."

Stage 1: WW1.  There weren't enough rifles.  When the National Guard was federalized they activated "State Guard" units and needed to arm them.  There are records of trapdoors being issued and the purchase of the Ross rifles was for similar causes.

Stage 2:  Dunkirk.  When the Brits were tossed out of France they had no weapons for the home guard.  Shotguns were rounded up and the NRA took donations here and shipped a bewildering array of guns to them.  The shortages of arms was a recent memory for them.

Stage 3:  "Springfield."  M-1903s were useful.  A request for donations of "Springfield Army Rifles" resulted in a lot of "Springfields" being turned in.  They held a War Bond raffle in my hometown with a Springfield musket being the prize.

Stage 4:  "Morale."  Air Raid Wardens in Kansas City?  Who's going to bomb it - Okies?  Metal drives, etc.  "Morale."  Doing something for the war effort.

They'd pretty much burned up the supply of Krag ammunition before WW1 and had to restart it for that war.  I'm unaware of them restarting it during WW2 so they'd be well oiled clubs.

Everybody points to trapdoors and claims they wanted them for line throwing guns.  I disagree.  I think those are also along the same line as the Krags as they had dedicated line throwing guns and they weren't trapdoors.  I say this as I'm sitting on a manual showing the standard line throwing kit and the gun isn't a trapdoor.

So I don't believe there was a specific purpose or need.  Simply happenstance.