Doug Nixon said in the 121004 MMD: "I am currently building a set of
trumpet pipes (Wurlitzer 105 style) and need to know the hardness specs
(Rockwell) for the reed brass."

As someone who taught Strength of Materials to engineering students for
decades, I offer the following.  The hardness of a metal affects only
the "yield point" of the material, not its "modulus of elasticity."

The yield point is the stress at which the piece will not spring back
to its original shape.  Normal use of a reed will never move it very
far.  Even soft brass should work, but is easily damaged in rough
handling, so it should not be a first choice.  Yield point is not a
factor in the vibration equations for a beam or reed.

The modulus of elasticity, on the other hand, is a major factor in the
vibration equation.  It is essentially a measure of the stiffness of
the material.  There may be slight differences between various brass
and bronze alloys, but tuning will compensate for these differences.
Materials other than brass may be substituted, but different thickness
will be required to compensate for the difference in modulus of
elasticity.

Put another way, the specs don't give the hardness because "it don't
matter."

Wallace Venable