I started my service with an M-1 in the mid-60's and IMO, most M1 thumbs that I'd seen were awarded while proudly doing the "manual of arms", not while loading an en-bloc.
James K - I'm with you. It was always just an M-1 to us. I never even knew it was a Garand until many years later. Of course, the M-1/M-2 Carbine was just called either a Carbine or POS.
Today, in all honestly, I do think much more highly of the Carbine than I did back then.