I've been pesting tree rats for a few years now. This past year (so far) I only took about ~110 and that is about a third of what I was taking in my backyard for the last couple of years when I kept accurate records... it was probably higher than that before I started keeping records!
So, I would say I am a successful pester.
When I started, I read a lot of forums and the consensus was to take head shots. Well, I tried that and even with what seemed to be perfect shots, I still had to make PBR follow up kill shots most of the time. The problem was/is that making a good, clean head shot leaves little room for error.
So, I studied tree rat anatomy with my attention focused on the pump that runs everything... the heart.
Once I understood where the pump was located, I dedicated myself to making pump (heart) shots and guess what?
I haven't had to make those close range follow up kill shots anywhere near so often. And for you naysayers who say I just don't talk about it, you haven't viewed my posts listing my kills... have you?
Anyway, this was ALL done with airguns shooting right around 12fpe at the muzzle. Pass through was common even at 40 yards, but I kept the power at this level for the trajectory that I had become used to.
Also, I use HIGH powered scopes and leave them at the highest setting unless lighting conditions force me to back off/open up the scope.
In any case, if you think you NEED more power or a larger caliber, first look at how accurate/precise you are with your shots.
LOCATION, LOCATION, LOCATION!
Haven't heard this in a while here, but it always annoyed me when I read someone saying their gun was "boringly accurate".
Well, if it is, then there is NO excuse for missing a heart shot or even a head shot on a tree rat! (chuckle)
BTW, there are no "Ninja" tree rats, just bad shots behind the gun. (smile)