  We compare model predictions to observations of star counts in the red giant
branch bump (RGBB) relative to the number density of first-ascent red giant
branch at the magnitude of the RGBB, $EW_{RGBB}$. The predictions are shown to
exceed the data by $(5.2 \pm 4.3)$% for the BaSTI models and by $(17.1 \pm
4.3)$% for the Dartmouth models, where the listed errors are purely
statistical. These two offsets are brought to zero if the Galactic globular
cluster metallicity scale is assumed to be overestimated by a linear shift of
$\sim 0.11$ dex and $\sim 0.36$ dex respectively. This inference based on RGBB
star counts goes in the opposite direction to the increase in metallicities of
${\Delta}$[M/H]$\approx$0.20 dex that would be required to fix the offset
between predicted and observed RGBB luminosities. This comparison is a
constraint on "deep mixing" models of stellar interiors, which predict
decreased rather than increased RGBB star counts. We tabulate the predictions
for RGBB star counts as a function of [Fe/H], [$\alpha$/Fe], CNONa, initial
helium abundance, and age. Though our study suggests a small zero-point
calibration issue, RGBB star counts should nonetheless be an actionable
parameter with which to constrain stellar populations in the differential
sense. The most significant outliers are toward the clusters NGC 5025 (M53),
NGC 6723, and NGC 7089 (M2), each of which shows a $\sim 2 \sigma$ deficit in
their RGBB star counts.
