These are like $60 chokes.
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=221941462
The Browning site list it at .102 constriction so it sounds like a .640
Kurt
You guys migh be right. I remember seeing some of these chokes in a gun shop here years ago. But I am not too familiar with them, but new they were expensive chokes. Of course that don't make them good. .640 would be a little tight, but then again .643 on a lot of the Tru-Glo chokes seem to work well in a lot of guns.