Marksmanship training teaches recruits the fundamentals of marksmanship with their M-16A2 service rifle. This training takes place over two weeks, the first of which is called Snap-In Week. During this week, recruits are introduced to the four shooting positions (standing, kneeling, sitting and prone) and a Primary Marksmanship Instructor shows recruits how to fire, how to adjust their sights, how to take into account the effects of the weather, etc. Recruits also have the opportunity to fire on the Indoor Simulated Marksmanship Training machine. During the second week of marksmanship training, recruits actually fire a known-distance course with ranges of 200, 300 and 500 yards. Recruits prepare for rifle qualification on Friday of that week.