The Interceptor Body Armor (IBA) has significantly improved Soldier combat survivability, but in what ways does it change rifleman lethality? A July 2005 study quantified the effects of Soldier equipment on lethality through multi-factor logistic regression using data from range experiments with the 1st Brigade, 1st Infantry Division (Mechanized), at Fort Riley, Kansas. The designed experiment of this study estimated the probability of a qualified US rifleman hitting a human target. It used the rifleman's equipment, posture, Military Occupational Specialty (MOS), and experience along with the target's distance, time exposure and silhouette presentation as input factors. The resulting family of mathematical models provides a Probability of Hit prediction tailored to a shooter-target scenario. The study showed that for targets closer than 150 meters, Soldiers shot better while wearing body armor than they did without. Body armor had a negative effect for targets farther than 200 meters, and this could significantly impact the employment of the Squad Designated Marksman. The study also showed that the kneeling posture was an effective technique and recommended standardized training on this method of firing.
 
The outer tactical vest consists of a Kevlar weave that's will stop 9mm pistol rounds. Webbing on the front and back of the vest permits attaching such equipment as grenades, walkie-talkies and pistols. The Small Arms Protective Insert (SAPI) is made of a boron carbide ceramic with a spectra shield backing that's an extremely hard material. It stops, shatters and catches any fragments up to a 7.62 mm round with a muzzle velocity of 2,750 feet per second. It's harder than Kevlar.