On average, the human body measures 455mm wide from shoulder to shoulder. The maximum grouping standard that a soldier must produce onto target in order to be considered as a potential candidate on the renowned Royal Marines Sniper course is 50mm from a 100m distance. The reason being, is that this grouping applied to his target at further ranges will allow the soldier to accurately engage targets out to 900m, and achieve first round hits, meaning that no follow up shots are required and the element of surprise has been maintained.
Before passing the shooting phase of the Sniper selection course, groupings must be down to 35mm at 100m, which equates to a 455mm grouping (average shoulder to shoulder) at 1.3km. This allows the potential sniper to achieve his 8 out of 10 round hit rate required to pass when engaging his target from 1200m away, whilst having correctly accounted for all external factors such as wind, gravity, drag, temperature, humidity, altitude, spin drift, etc.
Lets take altitude for example. If you have obtained your DOPE at sea level, and this is where you are most comfortable shooting, you now go on a lads shooting holiday up to the mountains and find yourself at a higher altitude which has far thinner air, lets say 2500m above sea level. If you are unaware of how to account for the affects of altitude, you could find yourself hitting your target (or missing your target) by a shot impacting 75cm high when engaged from a distance of 500m. This is just simply due to neglecting the effects caused by altitude. You haven’t even begun to explore the other external factors that effect your bullet’s flight path.
You can see how things can start to go horribly wrong. Also remember that learning how to shoot at long range even if you do not intend to, is extremely valuable because it will greatly increase your accuracy at shorter ranges.
