I just got a Remington 870 Super Mag with a 23" barell, and I have found that it doesn't pattern very well with the factory full choke. I was shooting the Winchester high velocity turkeyloads 3.5 2oz. 6shot. Was it just the shells I was shooting that made it pattern so bad, or is it the choke. I've heard the factory choke doesn't do well with any ammo, so what choke and ammo combination have you found to pattern well with the 870?