Penetration Calculations

There is a question of what do I use to generate my gun penetration tables. I do not use NaaB or any other formula like De Marre formula. Even though I now have most of the velocities of shells, I didn't always. I average all available data after normalizing it.  This can result in data points somewhat inconsistent with velocity graph slope.

The above data point plot are averaged to get a penetration average.   As a result the line may not be as smooth as a ballistics curve.   The data extends beyond the last data point to around 4000 meters using curve fitting.  The lower picture shows the program with the data displayed.