How much does a full grown adult diamondback rattlesnake weigh?

In 1987 I personally saw a large eastern diamondback that had been shot by security guards earlier in the day in a swamp near a medium caliber test range just northwest of Lakeland, Florida, less than 2 miles south of I-4. The snake's head had been severed, but I estimate the length of the snake's body was in the range of six to seven feet. What amazed me was the girth of the snake's body, which I estimate to be well in excess of twelve inches at the center. I have read many descriptions of the size and weight of eastern diamondbacks, some of which say a max of 15-20 pounds, some say up to 15 kg. I understand that this may appear to readers as an exaggeration, but I estimate that the body of the dead snake weighed somewhere in a range of 40 pounds of more. I work out regularly, so I know what 40 lbs. means. The head of the snake was very large, approximately six-plus inches across. Had I known then what I have read about these snakes, I would have urged the guards to take the specimens (there were two, the second also quite large but not nearly so) to an authority for examination, but unfortunately I did not. I'll be happy to answer relevant questions, but most of what I have is presented here.