I can attest from measurements I have made myself, that some well-known American companies are quite fraudulent with their claims for pack volumes. They were not at all repentant when I challenged them.
One known American company was selling a day pack with a claimed volume. The prototypes I was sent for review were about half the claimed volume. I asked how this could be. Reply was along the lines of: Oh well, what we sent you were just prototypes the Chinese company made from our designer’s sketches. We didn’t think you would actually use them or measure them.
And the buckles on the shoulder straps were non-locking.
Cheers