It is hard to tell when a rattlesnake is dead.
I shot one near 5' in length with the best head shot I can imagine. It kept moving.
So I cut its head off. It kept moving for about two hours. I used to have a video of it moving without the head. All I could find was a pic:
Note that it is still able to contract its muscles.
NRA Life Member - Orange Gunsite Member - NRA Certified Pistol Instructor
"When plunder becomes a way of life for a group of men living together in society,
they create for themselves in the course of time a legal system that authorizes it and a moral code that justifies it." Frederic Bastiat