How's your dexterity? I don't shoot 177,well I prefer to shoot 22 over 177 simply because it is easier to grip and load the 22s. Once you get further along in age or injuries or both this becomes a factor. I believe the 22 is the more common or is becoming the universal caliber for air-rifles. It use to be only the 177, never heard nor knew of another air rifle caliber back in the day that was not a 177. lol that's been awhile ago. Competition being the acception for now but from what I see this is changing to 22. I know from exp that the 22 will end any problems with Mr Skunk, Possum, Raccoon,or Squirrel at the distance you present. If I were to use a 25 caliber implement I myself would have concerns along the lines of pellet down range distance & energy. Please try and test a variety of pellets to determine which pellet is most accurate and effective for your tool of choice before you elliminate said pest . Best of luck