Kzone is correct, if you get serious about the sport, #1 go have your gun fit to shoot where you look. My 1st shooting coach made me take the beads off my gun so I wouldn't look at them & learn to shoot where I looked. #2 pattern your gun at 20 yards with a tight choke to see where your barrels are shooting, 50-50, 60-40, 80-20, etc. Amazingly I have seen barrels that one barrel shot 8" right & the other 8" left. Imagine that at 40 yards! My custom o/u I had made to shoot 55/45, my preference. And, I live 20 minutes from Briley & been there too many times & spent too much money. They make their own chokes & will make custom chokes for you. I've shot more Briley's than I can count but that being said, I prefer extended ported Rhino chokes. I just think Rhino's patterns are more consistent.
JD