Racquet Sports Austin

I used to use an old Prince Force 3 racquet. I wanted to weigh it so I put it on my scale and it read 0.8 lbs. I went online and converted to ounces. 0.8 lbs = 12.8 oz. And the strung weight of Federer's racquet is 12.5 oz. I'm just wondering if I did something wrong and why people say that the Wilson K Six One Tour is so heavy, if the racquet I played with as a child is heavier. Is it because it's old or something? Just want to know because if my racquet is heavier than one of the heaviest racquets on the pro tour, I should have no problems with the heavy racquets of today. Thanks for reading and please answer. (Oh and yes I did weigh the racquet correctly. I stood it up on its handle at the center of the scale. And I was not touching it.)