I figure the title I used previously might be confusing so I am posting this question again. The Night Train use Ball Cal. 124. Which I assume is a modified ETA 2824. Jeremy once mentioned that all Ball Caliber are based on "Top" grade ETA movement. The other models using ETA movement are simply equipped with "Elabore" grade movement. Below is a some of difference between "Elabore" grade 2824 and "Top" grade 2824, taken from the ETA datasheet.
Barrel spring Nivaflex NO/ Nivaflex NM
Shock absorber Etachocs/ Incabloc
Pallet stones Poyruby/ Red ruby
Balance wheel Nickel gilt/ Glucydur gilt
Hair-spring Nivarox 2/ Anachron
Adjustment 3-position/ 5-position
Average rate (+-7s/d) / (+-4s/d)
So, there's a huge difference between a Elabore grade 2824 and a Top grade 2824. I would like to know which grade of 2824 is used in the Firemen Night train. I suppose some brave soul who remove the back of their night train and look at the shape of the balance wheel would immediately solve the mystery. But I don't imagine many night train owner would entertained by this idea. So would anybody from Ball, perhaps Jeremy shed some light on this? Thank you.