Event screening of large‐magnitude events (Mw≳5) based on mb:Ms is revisited to account for the effect of the source corner frequency relative to the fixed frequencies of the long‐period Ms and short‐period mb. For large events this source effect increases the slope of mb:Ms relative to the 1:1 value expected for small events. The effect is demonstrated in the large earthquake mb:Ms population and in the behavior of large theoretical explosions that are consistent with the more limited explosion population. The behavior is used to create a more conservative screening criterion that ensures large explosions are not inadvertently screened out by mb:Ms, while not appreciably decreasing the number of screened earthquakes. This change also makes the variance of the earthquake and explosion populations more equal, which is of utility in statistical analysis. A slight trend in the explosion population and a case study of two large U.S. underground nuclear tests provide support for adopting a more conservative approach.