well the .22 i would use in Longs and no father that 40 yards and make it a head shot. 12 gauge use #4 shot in 2 3/4 or 3 in. out to about 30-35. I don't know about a 20 gauge but the specs are probly about the same. The 12 gauge is probly more effective than the .22 or 20 gauge.