What fooled me about the drawing was my own stupidity. I saw the measurement on the outside right indicating 3.000". I took that to be the case length (same as .500NE). I see now it's the OAL. Sometimes your eyes don't see what they are looking at.

I also now remember that the 50-140 is the Sharps cartridge that is most similar to the .500NE.

Silly me.
Curl