http://www.ex-astris-scientia.org/articles/defiant-problems.htm
If you go with the 120m length, you get approx. 1:382
If you go with the 170m length, you get approx. 1:540
If you say to heck with it, and call it 157m, then you get a nice 1:500.
To be honest, I don't care cause the darned...