I have both factory Encore chokes. One is ported, the other is not. I also have IC and Kick's GT in similar constrictions (.660 and .665, respectively).
They all pattern differently. It probably had a lot to do with how the choke strips the wad and also maybe some pressure considerations.
I got 218 in a 10" circle at 40 yds with the ported factory choke.
I hunt with the GT because it gives a more even pattern at 40 and the 30 is just nasty.
Hope that helped.
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