  NA61/SHINE is a large acceptance fixed target experiment at the CERN SPS
which studies final hadronic states in interactions between various particles
and nuclei. The main topic of this contribution are preliminary results for
mean negatively charged pion multiplicities $\langle \pi^{-} \rangle$ from
central Ar+Sc and Be+Be collisions. The data were taken recently by the
NA61/SHINE collaboration for a wide range of beam momenta. Measured rapidity
distributions $\frac{dn}{dy}$ were extrapolated to unmeasured regions to obtain
total multiplicities $\langle \pi^{-} \rangle$. A new scheme to calculate the
mean number of wounded nucleons $\langle W \rangle$ utilizing the EPOS MC model
is described. Using data from other experiments, a comparison of $\frac{\langle
\pi \rangle}{\langle W \rangle}$ for different collisions and beam momenta is
discussed
