I have a Remington Express 870 Magnum 3"
I had a Modified choke but bought a Extra Super Full Remington Choke and I can have a tight group at 40 yards easly and have got a turkey at 60 yards no problem. Every guns diff but My best hunting buddy has same set up and has gotten a turkey at 60 yards also.
I use Winchester H.V Supreme (black shells) #4's. But I have tried out the Winchester Extended Range and had a tighter group at 60. So I easly think I can get a turkey at 80. I wouldn't tho unless it was a super tough situation. I prefer them up close at 40-30 yards but thats a awsome set up I have found for my gun
Cory