Of all nuclear physics experiments none are more fundamental than ``elastic'' $p,p$ and, secondarily,
$p,d$ or $d,d$ scattering. Recognizing that these particles are themselves composite, ``elastic''
scattering may be accompanied by temporary internal rearrangement with undetectably small energy loss.
%
This paper argues that correct calculation of the spin dependence of $p,p$
(and other charged particle) elastic scattering, must account for a previously-neglected relativistic effect
of ``$G$'', the anomalous magnetic dipole moment (MDM) of the scattering particles. The paper
describes storage ring scattering configurations capable of confirming this contention.
%
Especially important experimentally for protons is the existence of ``perfect'' (greater than 99\%)
proton-carbon scattering polarimetric analyzing power $A$ at $K$=183.1\,MeV laboratory kinetic energy
and correspondingly high nearby.
%
Possibilities:
(i) In a storage ring collider with counter-circulating proton beams, each with energy up to
$K$=200\,MeV, the final spin states of coincident scattered protons can be determined
with high probability for a significantly large fraction of all scatters, both prompt and delayed.
For comparison with current descriptions based on proton scattering from a hydrogen target fixed in the
laboratory, this corresponds roughly, to proton kinetic energy $K$=400\,MeV in the laboratory frame,
barely below the pion production threshold.
%
(ii) In a ``DERBENEV-style'' figure-8 storage ring, independently polarized, diametrically opposite bunches
on orthogonal orbits can collide at the beam crossover point with symmetric $K''\approx200$ MeV energies
in a slow (transversely) moving frame.
%
(iii) Alternalively, $p$ and $d$ beams can counter-circulate at the same time in a small racetrack
shaped ring with superimposed electric and magnetic bending. In this case the scattering would be ``WOLFENSTEIN-style'',
with collinear incident orbits (at the cost of significantly inferior polarimetry for the deuteron beam).
%
To investigate the consistency of quantum mechanics and special relativity it is proposed to implement
options (ii) and (iii) in the COSY beam hall.