FWIW, the rail on my Mausingfield is steel, and I received it back in March (of course, it was an in-stock action at the builder... so there's no telling when it was manufactured).
I guess I was assuming that the newer ones were aluminum since the ones being sold on the website as replacement rails are aluminum. My first one is like s/n 42 or something and it's definitely a heavy steel rail.
My action was from 2015. When I contacted Ted I just asked for the torque specs and he did not ask for vintage or material of construction.
Just said 40 to 45