When i first started reading responses on here, money is the first thing i thought of also, a 12 will prob reach farther than a 20 but realistically, eaven for an experienced hunter you want them within 40 yrds, 35 or less i think. At that range a properly patterned 20 with a good shot will kill them just as dead as anything else. Being new hunters the closer the better no matter what they're shooting. But eaven a 20 ga in a single shot with a 3" mag is gonna knock em pretty good. Just make sure whatever you go with they get some trigger time so they know what to expect when the action hits!