In cover a moving snake that is fleeing can be had to hit with a single bullet. I recalled one that got away from me that way. About a month later what I believe from the makings was the same water moccasin I spotted from the tractor moving away. I had a .38 3 inch barrel gun with commercial shotshells; ran the snake down and from maybe 10 feet fired at it to stop it. Got a little closer and put some in the head. And then got really close like a few feet and really peppered the head well.