AutoCAD Inventor :: Surface Contact With Initial Gap?

I'm working on a FEA of a climbing carabiner (oval-shaped; one side of the oval is a gate which opens and closes allowing a rope into the carabiner).

The gate of the 'biner has a hook which attaches to the "nose" of mainbody/biner.  However, this hook does not engage until the biner slightly deforms.

I've attempted to use the separation/no sliding contact option, but the solver behaves as if there is no contact occuring.  The nose simply passes right through the gate hook.

The initial gap of the system is about 0.040".  That means the nose must deflect 0.040" before the contact surface comes into play.