Senwes Scenario June / July 2019 - Page 37

HUNTING How do I determine the accuracy of my firearm? To shoot a 3-shot grouping at 100m, with the shots cutting one another, must certainly be an indication that my rifle is accurate. But is it the only way of determining the accuracy of my rifle?  By Jan-Lodewyk Serfontein Hunting expert I n reality it does not happen very often that three shots cut one another on your target. The setting of your rifle can be 100% accurate, with perfectly reloaded ammunition, and it can hap- pen that the desired grouping cannot be achieved on a given day. This may be due to external factors affecting the trajectory of the bullet, which push it away from its target. In addition to external factors such as wind and temperature, a number of other factors also affect the accuracy of your rifle. The technique of a shot is a determin- ing factor in finding the target. The tech- niques to be mastered by a shot include the way of pulling the trigger, cheek posi- tion and dealing with the kick-back action. Should these variables not be dealt with in exactly the same way every time, your rifle will not be accurate. Poor quality telescopes and shots with weakening vision, can also be deter- mining factors in the accuracy of a rifle. Telescopes play an important role in the placement of a bullet. In addition to the importance of being able to see what you want to shoot, the telescope also has to be accurate. The cross-hair of an accurate telescope does not move around by itself and has to be set accurately if necessary. Due to the fact that a barrel which moves 0.016 degrees away from the target will result in an inability to shoot an inch group- ing at 100 paces, it is important to have a very accurate telescope. If the external factors and the technique of the shot have such a huge effect on accuracy, there has to be another way in which to determine the accuracy of a rifle. With technology improving everything, including rifles, there has to be something that we can use to determine the accuracy of a rifle. In an article published on the website on 20 June 2015, titled Load Development (Part 1 of 2), the writer explains how he approaches load devel- opment. One of the ways used by him to determine an accurate load, is to measure the speed of every shot and to use the load in respect of which speed has the smallest extreme distribution. The extreme distribution of speed of a group of load- ings is calculated by deducting the lowest speed from the highest speed. The result is then the extreme distribution of speed of a specific load. The article mentions that the targets which have good groupings, compare well with the loads with very low extreme distribution in respect of speed. Can we therefore use speed as an indica- tion of accuracy? The speed at which a bullet leaves the barrel of a gun, is determined by internal ballistics. Should the internal ballistics of two bullets be the same, they should find the same target should the technique of the shot and external factors not be taken into account. The speed at which a bullet leaves the barrel of a gun determines the trajectory of the bullet. Should every tra- jectory be exactly the same, every bullet should find the same target. Before simply accepting that speed is a good indication of the accuracy of a rifle, we have to test it. If possible I should measure the speed of my rifle during load development. The speed which I measure is for purposes of determining the tra- jectory and not necessarily to determine whether speed and accuracy have a direct correlation. After load development I found that a loading which does not group well, does not have an extreme distribution in speed of more than 10fps. Therefore, I will have to do a test to determine the correla- tion between speed and accuracy. I will let you know of my findings! SENWES SCENARIO | WINTER 2019 35