I use a Carlson's brand "Coyote" extended choke. I believe its .665 or .660 in 12 gauge. It patterns very well with 4 buck in a 26" barreled Rem 870. If you search on Ebay you can find barely used ones on the cheap. I picked up a Carlson's Longbeard XR on there for $25. It was out of the package but you wouldn't know it from new.