  Results of recent experiments on the OMEGA Laser are presented, demonstrating
the ablator-driver shell collision relevant to the outer two shells of the
Revolver triple-shell inertial-confinement-fusion concept [K. Molvig et al.,
PRL~{\bf 116}, 255003 (2016)]. These nested two-shell experiments measured the
pre- and post-collision outer-surface trajectory of the 7.19 g/cc chromium
inner shell. Measurements of the shell trajectory are in excellent agreement
with simulations; the measured outer-surface velocity was $7.52\pm0.59$
cm/$\mu$s compared to the simulated value of 7.27 cm/$\mu$s. Agreement between
the measurements and simulations provides confidence in our ability to model
collisions with features which have not been validated previously. Notable
features include the absence of $\sim$40 mg/cc foam between shells commonly
used in double shell experiments, a dense (7.19 g/cc) inner shell
representative of the densities to be used at full scale, approximately mass
matched ablator payload and inner shells, and the inclusion of a
tamping-layer-like cushion layer for the express purpose of reducing the
transfer of high mode growth to the driver shell and mediation of the shell
collision. Agreement of experimental measurements with models improves our
confidence in the models used to design the Revolver ignition target.
