I've used commercial and made up my own at times.
Effective range is about 6-8 feet. Unless you're dealing with some of those gawdawful gator size rattlers they have in the south or water mocasins that get mean, I figure:
1) A snake 6-8 feet away is not a danger. At least not as much a danger as trying to Wyatt Earp the booger.
2) Closer, a stick works better for our southwest rattlers, flip it out of the way if possible, turn him into a hatband otherwise...
I've never used in semis, used .22, .38 from Speer in revolvers, made my own in .41 Maggie and .45 Long
Colt.
Tom