I've tested the CCI .22 shotshell. Effective for what its designed for ie killing rats or snakes. The CCI .22 is loaded with #12 shot. This effective for the intended purpose and is probably better than #9 shot because you get a denser pattern ie more likely to hit a vital. 3 metres is the maximum distance I would use it for.

ps Recommend wearing eye protection. That tiny shot can really bounce back if it hits a hidden stone or other hard surface.