i beleive it because my dad showed me a pic of a huge rattler he killed in florida when he wasin his 20's, my dad was 6ft at the time. he held the snakes body with his arm straight up in the air and the snake had 2ft of his body still curled on the ground so thats about a 9.5-10 footer my dad killed, but all the other one's he found were way smaller...
Looks like a common 5-6 footer that might weight 12-15 pounds. Its a shame the fellow had to kill it.