I've shot enough critters with .22 shot shells to know that there is no way I'd ever intentionally go up against a 3' + ratter with it. If you do, the range better be measured in inches and not feet. Closer than I care to get.
The G19 has tallied up 6 rattlers, one copperhead and one water moccasin this summer. You don't need shot shells, just aim better.
