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.