It's the 9th picture that Scott posted about. It shows the inner pad wear from a bayo band...
M1Carbine Saginaw .30 Carbine : Semi-auto at GunBroker.com
Another one,
Type III bayo band shadow....Picture #4
US GI WWII Inland M1 Carbine NON IMPORT : Curios and Relics at GunBroker.com