Rattlesnakes are not very agressive if you pay attention and don't get to close, especially on chilly days. A birdshot handgun works well, now days I carry a Judge with 410 birdshot in snake country. A word of caution though, I came across a rattlesnake when I was hunting deer with my 44Mag handgun. It was a small one and all coiled up ready to strike. I just overshot him and the resulting dirt explosion lifted him up and flung him onto my boot. If you have never seen a fat boy dance, you should have been there.
