You'll have to shoot it yourself to figure that out. Other than that all you are getting is opinions, not answers.

A good aftermarket choke for an economic price is the HS Undertaker. With a 20 gauge, I'd shoot plated #5 shot. Winchester.. black box... 3" #5.... = dead turkeys!

My girlfriend's 20 gauge Beretta works best with an Improved Modified choke and 3" #6 Hevi-13. It will do the job at 35 yards, but not much more.