I would not get a push/pull call. IMO----I don' t like how they sound. I think you would be better off getting a Lynch 101--Fool Proof One Sider. I have both calls. I' ve killed birds with the One sider and have not with a push call---(Quaker Boy Easy Yelper) Now the easy yelper stays at home & I use the one sider.

As far as shot size. I think you said you were using a 20 guage. If so I would use # 6 shot & a full choke. In a 20 guage I don' t think there would be enough pellets in #2 and probably not enough in #4 either.

Now if you were using a 12 guage, then I would pick #4. That' s what I use, I like the big holes it makes on my targets.

FYI--- I' ve taken or called in over 30 gobblers in the past 10 years. All Merriam' s here in Colorado.