I've been using a 20gauge the past couple of seasons and like everyone else has been saying, it's been plenty to knock down a bird. I shot one a couple of years ago with it at just over 40 yards while he was pecking on his dead buddy and he never twitched. I think it a full choke in it though and I was using #4's. I've also guided for a man and his 12 year old son (at the time) that was using a 4-10. He killed 2 turkey with it in one morning. I had him wait until they got within about 15-20 yards, but he killed both with one shot. He then hit a big tom later in the morning about 30 yards, but it literally sounded like they bounced off the birds feathers.

i got 2 last year. worked just fine... and a lot lighter to haul around.