What size buckshot were you using? I would prefer to use birdshot on a snake like that to reduce the danger of ricochet, damage to property and such.
I have sometimes thought that if I were in Florida and had the occasion to dispatch one of those awful pythons, I would use a tightly choked 12 gauge (which I've got in the form of a 71-year-old Winchester Model 12) loaded with a charge of #2 birdshot and go for a head shot.
Why would you kill a python?
Nevermind, just googled, you are probably talking about Burmese pythons.