Støy fra rifle : følsomhet for variasjon av kaliber, løpslengde og kulevekt

Military and civilian firing ranges must conform to strict noise limits. One way to decrease the noise level from a firing range is to change to a weapon that makes less noise. One motivation for this study was a contact we had some years ago with The National Rifle Association of Norway. They considered the idea of buying 5.56 mm ammo for users, to motivate them to change from 6.5 mm rifles. However, the resulting effect on noise from the range was not clear. The same question is relevant for military weapons. New weapons are continuously introduced into the armed forces. In this process claims will be made about the noise from these new weapons. The problem is that people are basing these claims on experience with weapons of different caliber which also differ in many other aspects. To deal with this problem we have considered the sensitivity of the noise level to variation in caliber, length of the barrel and weight of the projectile, keeping other parameters unchanged. The results in this report can be summarized as: • 6.5 mm makes 3 dB more noise than 5.56 mm • 7.62 mm makes the same amount of noise as 6.5 mm • The lightest projectile makes 1 dB more noise than the heaviest one • Ammunition called “recruit” makes 0.6 dB less noise than “normal” 6.5 mm ammunition • 67 cm barrel makes 1 dB more noise than 74 cm barrel • 67 cm barrel makes 0.2-0.3 more noise than 70 cm barrel