  We employ a simple multiple scattering model to investigate the inclusive
reaction p + A --> p + X for projectile momenta in the 100-200 GeV/c range. We
find that data are consistent with a class of interaction models in which the
stopping power of nuclei is rather low. We discuss extrapolation to ultra-high
energy and the application to interpretation of cosmic-ray air showers at
energies up to 10^20 eV.
