The effectiveness of shooting was tested in both prone and standing positions unsupported while wearing a new prototype infantry fighting equipment system developed under the Land Warrior (LW) program. Volunteers (n=12) were male infantry soldiers who were experienced marksmen. Volunteers shot while wearing three equipment configurations: the Battle Dress Uniform (BDU), BDU and the conventional fighting load (CONV), and BDU and the LW fighting load (LWFL). Significant differences (p<0.05) in distance from center of mass (DCM), shot group tightness (SGT) and percent of targets hit between equipment conditions were seen. Shooters shot approximately 42% farther away from the target center, had shot groups approximately 214% more disperse, and took 38% longer when shooting prone with the LWFL compared to the CONV conditions. The principal cause of shooting impairment while shooting prone with LWFL was the contact between the hard pack and the helmet preventing the shooter from properly lifting his head to see the target. Generally, when designing equipment, engineers should take into account performance under all body positions likely to be encountered in military operations. These results have demonstrated that both the standing and prone positions for shooting need to be considered when designing combat equipment for the fighting soldier. Relevance to industry The effect of a new piece of fighting equipment carried on the back as part of a soldiers' backpack was studied. The primary implication is for the military, but indirectly the results are important to any individual who wears a protective helmet and equipment on their back (construction workers, race car drivers, fire fighters, football players, etc.). A worker's equipment must be functional in all body positions that he/she may find themselves in, as opposed to just the standing anatomical position.