Chokes for buckshots
First of all excuse me for my spelling I'm Mexican and I live in Mexico City.
I agree with Dfariswheel is good to start with a improved cilinder at short distance, but just for patterning purpose only. However, in my opinion regardless the shell, you should take in to consideration the game and the distance you are going to shoot at, since the 00 buckshot reaches longer distance than other shots such as 7 1/2.
Regards