Best Choke for Beretta Extrema 391

[Bamarich]

Shooting an original Extrema (not the Extrema 2) and will most likely will shoot Hevi-13 ammo (#6 or #7).  Currently can get consistent 250 pellets in a 10" circle @ 40 yards with a Hevi-Shot choke tube (constriction of .671).  However, I really drop off at 50 yards.  I'd like a combo that can produce more performance @ 50 yards... to know I have forgiveness if I misjudge distance.  If you have an Extrema, what has been your best combo?  Thanks.

[VAarrowslinger]

how big of a drop off at 50yd are we talking? are you still geting 130+?

[Bamarich]

Going from 250 to about 90... but it's obvious the pattern is falling apart at that point because of the way it's spread out.