This has probably been discussed before and apologies if it has -- I can do a search. But if anyone is willing to entertain me or re-entertain the subject matter, I am looking for an air rifle for an older colleague for pest busting but he will not want to deal with cocking a break barrel or lever cocking rifle or have to deal with PCP. Should I consider pump or CO2 for him? .22 cal presumably? Will these humanely dispatch small pests? Thanks for any suggestions.