This study examines the effect of body armor fit on marksmanship performance. Specifically, 1 does wearing body armor affect marksmanship performance, and 2 does the fit of the armor affect marksmanship performance. Fifteen male Soldiers participated in a marksmanship performance task using a weapon simulator in four different body armor configurations no armor, initial fit, increased and decreased size. Accuracy closeness to target center, precision shot group tightness, and speed transition time were measured. Accuracy and precision were not significantly different regardless of body armor fit. However, speed was degraded in the initial fit body armor size and the increased size configurations relative to the baseline and decreased size configurations. In other words, in the decreased size, Soldiers engaged targets as quickly as when not wearing body armor, indicating body armor fit may impede a Soldiers ability to transition between targets, thereby impacting mission performance.