The first one was a Copperhead, a good kill IMO.
The last three have just been what people call gopher snakes around here. Nonpoisonous rodent eaters. We've had a lot of rain this Spring and Summer, it's driving them out more.
Silat, I don't know if this is actually works or if it's just old legend. My father taught me while hunting as a boy. If you have a rifle and stick it out towards the snake. The snake will raise it's head right in front of the barrel as if to strike. making your shot easier. I never tried it. I rather shoot at one with a rifle or shotgun than get close with a pistol though. Espeically if your talking rattlesnakes, or cottonmouths.