In general using the bottom of the reticle will help you better find your range. At 20 meters or less range you should aim for center mass with the bottom of the reticle at about knee height. At longer distances you will have to progressively aim the bottom of the reticle up higher. At 100 meters you aim with the bottom of the reticle at head height. This won't help with bullet spread from left to right since it is an inaccurate weapon.