Last year I killed 2 gobblers with my 12 ga. and 2 with my 20 guage. All 4 died in their tracks. One with the 20 ga. was at 40 yards. Both guns are 870's. I use hevishot #5 in the 20 guage and it throws a great pattern. The only 2 differences I can tell between the 20 and the 12 is the amount of shot and a great amount of recoil difference. I'll most likely have the 20 with me on opening morning this year. It's lighter and like I said the recoil difference is really nice. That being said, I do believe that the 12 ga. is the gun of choice for most people. The most important thing is to know is how your gun will pattern before you go on the hunt. Good luck with the 20.