The old time gunmakers were just as opinionated and stubborn about their ideas of convergence as we are today. Each maker had what they thought was the proper amount of convergence built into their guns. From shooting huge amounts of shells at pattern paper, I can deffinitely tell you that upland guns were set to converge somewhere between 20 and 25 yards, but heavy waterfowl guns were meant to converge at 40 yards or more. There was really no set amount of convergence rate.
The rates listed for the Feather Weight L.C.'s is certainly correct, but that doesn't refleck on any other guns or makers. As stated before, that just tells you where they are pointed while at rest, and has nothing to do with where they will be pointed at the moment the shot leaves the barrels. The points of impact have to do with many different factors such as the load being fired, the weight of the gun, the length of the barrels and the amount of time the load is in the barrel,the general build of the shooter,etc. As you can see, the gunmakers were working with averages, for the loads fired in their guns, the expected game, and the antisipated distance that it would be shot at, and the general build of the people who were going to buy and use one of their guns.
I think you know that there is no one answer to your question, but this just touches on some of what affects the shot placement and convergence problems faced by gunmakers everywhere. Bob
