Not surprised. Sub-sonic HPs are the bee's knees for gray sq. They hit them hard, harder than HVHPs even though you see more damage with high-velocity stuff sometimes. Those soft HPs open fast, seeming to use up all the energy on expansion.
Step up to anything bigger, like a fox sq. and you want more pop to get the same effect. A coon knocked out with sub-sonic will come down fighting. You can make a guess on how a coon hunter views fighting based in part on what he chooses to use to dispatch the coon.
That's just my experience having used 22lr for years over tree dogs.
