I am sorry to say, every gun is different.
Even if we bought the same gun, side by side with one digit different in the SN, its most likely they would shoot the same loads differently.
The only way to find out is to buy a couple different boxes and go shoot!!
I can tell you what I have found preforma well on game... Close range Remington BUCKHAMMERS, Longer range REMINGTON Ultra Core lokts. This is for the 12ga. I havent shot too many with the 20, but the old Rem coppersolids worked well, too.
CW