Rifle shooting is a precise science where the combination of barrel and ammunition affects the bullet’s accuracy. This is mainly due to the gun’s ‘kick’, also known as recoil, as the bullet fires: transverse vibrations result from recoil forces in the rifle imparting on the back of the barrel. These vibrations cause a variation in shot accuracy.
Raphaël got the idea to develop a system and corresponding technique for analyzing and predicting how rifles perform with certain ammunition. Once Raphaël had his methodology in place, he needed some help testing the system, gathering data and analyzing the results, so contacted Brüel & Kjær.
“When I explained my research project to them, they responded enthusiastically,” says Raphaël. “They sent Henri Gérenton, who is an application engineer, to meet with us at INSEP (France’s National Institute of Sport and Physical Education) and do a half-day measurement session.”
To capture the data they needed, Henri and Raphaël placed two accelerometers – one vertically and one horizontally – at the extremity of the gun barrel and then recorded time signals of the shots in order to reconstruct the motion of the muzzle and the muzzle jump (the tendency of the front end of the firearm to rise up after firing).
The signals were recorded using Brüel & Kjær’s LAN-XI data acquisition hardware and PULSE™ Time Data Recorder software. They made as many recordings as possible in order to increase their statistics, and changed parameters such as the gun barrel, the ammunition, the gun itself in a systematic way, to achieve a more nuanced view of their results.
“Thanks to the measurements done by Brüel & Kjær, we have been able to determine the relative impact of some of the parameters on vibration and confirm the efficacy of different types of rifles and gear,” explains Raphaël. “That means we were able to calibrate my system for optimizing the barrel-to-ammunition match that will improve shooters’ gear accuracy during training.”