Have you ever been to a bass tourney weigh in? I have been to hundreds of them, and I can tell you from experience that a 6 or 6 1/2 pound bass is HUGE. I really think that you are underestimating how big a bass needs to be to weigh 7 pounds. For reference purposes, here is one that weighed about 5 1/2 pounds:
Here is another one that was just shy of 5 pounds:
I'm telling you that a legitimate 7 pound largemouth is HUGE.