as far as I can tell with my older 12 ga with a smooth bore 28" barrel and a selecta choke I use full choke ,, that was what I was told would be best keeps slug from wandering and I can hit what I'm aiming at , at around 40 to 60 yards within a 4 inch pattern.. gotta do more longer range practice to see how the pattern holds up but I like the remington slugger info may try it's all a larnin process