I would go with a 22 caliber rifle loaded with bird shot.
The range and pattern using .22 shotshells out of a rifled barrel is disappointing. However if you have a .22 smoothbore, they (especially the crimped type) are deadly. Keeps most of the pattern on a paper plate at 30 feet. Plus, even if pointed up at a 30 degree angle, #12 shot will only travel 100 feet.