I have no idea what they called the rifle in WWII. My dad used the '03A3 in basic and later qualified expert with the BAR. When I'm back home we have better things to talk about than what they called their service rifles then.
I was talking about pinching your thumb when you poke it into an action that hasn't been properly locked back. That was called M1 thumb when it was first described to me. The guy who told me about it wasn't a WWII vet, so maybe it doesn't count?
I do believe you won't get a M1, M14, M1a, or Garand thumb if you properly lock the bolt back before poking around inside an empty mag well or if you hold your thumb firmly on the top round and then pull it away smartly upon removal. At least no M1 I've handled would let the bolt fly home while my thumb was pressed down on the top cartridge. Having the back of your hand pressed against the bolt handle is added insurance.
Just relating my experience and couldn't care less when we started calling that particular rifle a Garand. I also don't worry about how to pronounce "Garand". I'm sure if he was alive he'd butcher my last name if he tried so I'll consider us even.