One thing to take note of with the shot--it won't work very well if the barrel of the .22 is rifled (has spiraling grooves cut into it to spin the bullets as they travel down the barrel). I remember when I was a kid that my dad, a crack shot, was having the darndest time getting rid of the rabbits in the garden with the same type of .22 shot shells you show in your photo. Then he realized that the rifled barrel was just spinning the shot wayward as soon as it passed the muzzle! Switched back to regular .22 shells and poof! ...no more rabbits.

There is a neat old e-book on project gutenberg http://www.gutenberg.org/ebooks/17243 Full Revelations of a Professional Rat-catcher by Ike Matthews that goes into great detail on how to get rid of rats. We used the rat shot years ago in a worn 22 but I have used them in a good rifled barrel with good results but I have never tested the pattern. Pellet guns will get the job done but takes accuracy.