Molecular dynamics (MD) was used to gain insights into grain boundary (GB) shear mechanisms in alloys that require GB mobility in a field of coherent precipitates. The area fraction of the Σ11 affected by the γ′ was systematically varied to explore how GB shear mechanisms change with increased number of precipitates. Without precipitates, local atomic shuffling accommodates the Σ11 GB shear; above an area-fraction threshold, GB shear required dislocation emission. In addition to precipitate area fraction, the transition in GB shear mechanisms may also depend on precipitate shape/size, temperature, and GB misorientation. These factors will be investigated in future work.