The Nitro Ammo Co. recommends a Rhino choke for their hevi-shot and they run about 80.00, I'm hopeing for one by spring, But I have shot a Rem. Ventilator the last couple years and fairly satisfied with it, It is a .655 ported choke and the Rhino they recommend is a .660 ported.

Maytom shoots the Nitro Hevi-Shot with a Rhino choke and he gets a awesome pattern.

See my post on here about my Nitro Hevi-Shot/Rhino choke experience. One picture included.