I have a BSA SuperSport .177. I have never hunted with it, just pest control around the house. What would be a good pellet for squirrel hunting and what is the effective range on squirrel sized game?
For up to 20 yds wad cutters.
For up to 30 yds hollow points.
For up to 50 yds dommed.
You will need to test fire several different pellets on paper targets located at the different intended hunting ranges to find out which ones groups the best and select those for hunting. A Straight Shooters pellet sampler is a good idea for testing an array of different pellets.
With a 14 fpe airgun as the SuperSport .177 the maximum effective range for squirrels maybe up to 50 yds, but the real limiting factor will be your shooting skill.