I have been using a 177 s200 just for rats for the last few years. It works, a few thousand pellets I know how it works.
I have just bought a s510 fac in 22 as I need something something for squirrels. Yes could bait and wait but no time. Quicker to thermal spot them in the trees hiding, then shoot them. Can't use the rim fire for that. The squirrel might be 50 yards away. So I bought the s510.
Used on the rats couple nights back as it has adjustable power, 11.5 at lowest with a 14.5 grain pellet
Turn it up with a 22gn to 29footpound
So far, works for me