(Bravo8500) wrote in
MDA on my local uncontrolled airport's NDB approach, and I don't
see the runway but can see directly underneath me, I could
legally slip down below MDA to try to bust out. Why? At MDA, I'm
below the 700 foot floor of the Class E airspace which puts me
in Class G. This would be the case at almost all uncontrolled
airports that have published instrument approaches. Does this
sound right?


I think that this reg answers your question.

Section 91.175: Takeoff and landing under IFR.
(a) Instrument approaches to civil airports.

Unless otherwise authorized by the Administrator, when an
instrument letdown to a civil airport is necessary, each person
operating an aircraft, except a military aircraft of the United
States, shall use a standard instrument approach procedure
prescribed for the airport in part 97 of this chapter.

(b) Authorized DH or MDA. For the purpose of this section, when the
approach procedure being used provides for and requires the use of
a DH or MDA, the authorized DH or MDA is the highest of the
following:

(1) The DH or MDA prescribed by the approach procedure.

(2) The DH or MDA prescribed for the pilot in command.

(3) The DH or MDA for which the aircraft is equipped.

(c) Operation below DH or MDA. Where a DH or MDA is applicable, no
pilot may operate an aircraft, except a military aircraft of the
United States, at any airport below the authorized MDA or continue
an approach below the authorized DH unless --

(1) The aircraft is continuously in a position from which a descent
to a landing on the intended runway can be made at a normal rate of
descent using normal maneuvers, and for operations conducted under
part 121 or part 135 unless that descent rate will allow touchdown
to occur within the touchdown zone of the runway of intended
landing;

(2) The flight visibility is not less than the visibility
prescribed in the standard instrument approach being used; and

(3) Except for a Category II or Category III approach where any
necessary visual reference requirements are specified by the
Administrator, at least one of the following visual references for
the intended runway is distinctly visible and identifiable to the
pilot:

Bob Moore