Using a pellet gun won't help you out with the city. It's all illegal. Shooting an Airsoft gun is as illegal as centerfire gun. In a fit of civic responsibility once, I emailed the city attorney once to verify that an Airsoft gun was legal. His answer was that any firearm that uses gunpowder or compressed air cannot be discharged in the city and that they'd prosecute. So, if you choose to obey the law, no pellets, bullets or BBs in Edmond.
Is it still legal to possess a hoe? My mom killed enough snakes with her garden hoe to fill up a truck.
Don't shoot it. You could do collateral damage (see above). A golf club works pretty well, and the irons make a pretty good snake stick if you know what you are doing.