Garand thumb is one of those things you only ever do once. I bet there isn't a person alive or dead that ever did that twice. I know I'll never do it again The main lesson I learned having one break my thumb for me...I don't care how strong you think you are, your pinky finger is not strong enough to hold the slide open while you depress the follower with your thumb.
Luckily my Grandfather gave me a lesson on reloading the Garand when I bought my first one. He said, it was the number one injury of him and all of his buddies in boot camp before being shipped off to Korea.