Jelly Head by Primos is a great choke. I use it in combination with a remington 11-87. I have had them group so tight that the actual wad has hit a turkey in the head when I shot him. Definitley a good choke and its not too expensive either.
not sure what my choke is but the numbers is .640 it patterns really well out of my 870 super mag i also have a kicks gobbling thunder it does well with 3inch winchester #4