Good morning Mr. Boylan: Thanks for the response. Some good info on that site. Learned about the forcing cone area also,read about it often,now I understand where it is. I'm 62 now and remember my Dad talking about chokes. He was strictly a 12ga. man. He used a dime. If it would not slip in the end of the barrel,it was Full,if it would slide in it was Mod. or open. That was all he needed to know. Simple, but I like the 16's and 20's and the fact that L.C. Smith did not mark most of their barrels complicates matters. Will do some more research. Bottom line is if I pull the trigger and the bird or rabbit goes down, all is good. Thanks again, Paul.