  We report the latest results of searching for possible new macro-scale
spin-spin-velocity-dependent forces (SSVDFs) based on specially designed
iron-shielded SmCo$_5$ (ISSC) spin sources and a spin exchange relaxation free
(SERF) co-magnetometer. The ISSCs have high net electron spin densities of
about $1.7\times 10^{21}$ cm$^{-3}$, which mean high detecting sensitivity; and
low magnetic field leakage of about $\sim$mG level due to iron shielding, which
means low detecting noise. With help from the ISSCs, the high sensitivity SERF
co-magnetometer, and the similarity analysis method, new constraints on SSVDFs
with forms of $V_{6+7}$, $V_8$, $V_{15}$, and $V_{16}$ have been obtained,
which represent the tightest limits in force range of 5 cm -- 1 km to the best
of our knowledge.
