I shoot an 835, but I don't shoot the Hevi Shot. However, the HeviShot is supposed to favor a more open choke, due to the density and hardness. The 835 is back bored to 10ga diameter and also favors a more open choke. I'd experiment with a regular full choke and may even try a modified with that setup just to see what I got and then choose from there. Me personally, I've got a TrueGlow gobble stopper and shoot Winchester Supreme HV #4's and get around 125 or so in a 10"circle at 30yds. That gives me around 20 to 25 in the head and neck. At 40yds I got around 75 in the 10" circle and anywhere from 12 to 20 in the head and neck. I didn't pattern it any further than that, b/c I usually don't shoot any further than that and the 'ole shoulder was a little worse for wear from 30 to 40 yd shots. Hope this helps. One other important thing, I also have a red dot scope on my gun and have the dot pretty centered in the most dense part of the pattern.