Quote Originally Posted by BMbikerider View Post
Autowind cameras have electronic shutters so there is nothing 'cocked' until the power is switched on.

The FM2 is mechanical through and through and the operation and accuracy of the shutter is dependent on a finely balanced spring tension. Leaving it cocked will upset that balance/accuracy so it is best left un-cocked.
Autowind camera still have the regular spring operated shutter. Electronically controlled shutter is only for the timing of the second curtain. It's still under the same stress if any. However, I read somewhere by Nikon that it's ok to leave the shutter cocked for a long time including fully mechanical shutter like the FM or FM2