Another skeptic here. I've heard this statement before. I've also heard the same thing about 45ACP.
Here's what SAAMI says about the 45 Colt.........
http://www.saami.org/PubResources/CC.../45%20Colt.pdf
And the 45ACP, just because I was curious........
http://www.saami.org/PubResources/CC...0Automatic.pdf
Jerry