Interior- and exterior ballistics
After extensive stalking or stand hunting, the moment comes when the hunter decides to shoot. Then it’s only a split second of accurate performance that counts. On the following pages we describe what happens in this short period between pulling the trigger and hitting the target, showing how Norma’s experience contributes to a controlled and reliable process. The design characteristics of the cartridge, including powder and bullet choice, provide optimal interior and exterior ballistics. The decisive element for shooting accuracy and effect on the game is the bullet. Its aerodynamics and weight are responsible for the flattest possible trajectory. Its penetration and mushrooming characteristics provide the instantaneous death which we owe to our quarry, and ensure that the meat is damaged as little as possible.
Interior ballistics is a term describing the process from the firing of the primer to the moment when the bullet leaves the barrel. It is extremely important to have the ignition and burning of the powder uniform from shot to shot. Consequently, we combine the right primer with the right powder in every load. By doing this, we keep the pressure at given limits and achieve best accuracy and velocity as well as reduced recoil.
1 After the trigger is pulled, it takes around 0.005 seconds before the firing pin reaches the primer.
2 The pin makes a spherical imprint in the primer, and fires it … … the cartridge is pushed forward by approx. 0.1 mm at the same time.
3 Very hot gases and glowing particles splash through the flash hole of the case. The powder ignites.
4 Increasing pressure pushes the bullet forward. When reaching maximum pressure, the bullet’s speed has reached approximately 300 m/s. From the firing of the primer it takes 0.0015-0.002 seconds until the bullet exits the muzzle.
5 When the bullet leaves the muzzle, the hot gases surround and overtake the bullet, continuing the acceleration for a few centimetres.
6 Because the barrel is always angled slightly upwards, the bullet’s flight starts about 3-5 cm below the line of sight.
Lands and grooves in the barrel make the bullet rotate. Long bullets need faster rotation than short ones. The twist typically varies from one turn in 8” to 16” depending on cartridge. It is important that barrel wear should be as low as possible in order to protect the barrel. In addition, the powder has to burn completely so that no further residues remain in the barrel. Both processes are guaranteed through a well thought-out construction of case, powder granulate and bullet.
7 If shooting distance is much shorter or longer than expected, the hunter may hold high or low, or else adjust the sights accordingly.
8 When shooting within usual distances the bullet hits the target at the exact aiming point.
A higher bullet speed and a higher ballistic coefficient lead to less bullet drop and less deviation caused by crosswinds.
Thanks to the bullet’s optimized trajectory and stateof- the-art design that is tailored to specific hunting demands, Norma allows the hunter to focus on hunting and shooting expertly without worrying about the ballistics of the ammunition. High quality and production standards provide a reliable and calculable performance of the bullet inside and outside the barrel.
WARNING: What is behind the target must always be considered, as bullets can travel several kilometres and cause unintended damage.