ballisticsresearch.net


The research data is organized under calibre, then by bullet and within that the firing series.

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9mm Parabellum, 9x19, (Luger):

125 Grain Howitzer Lead Round-Nosed Bullet

The research data tables for Series 1 & Series 2 show values for the Ballistic Coefficient, C, computed using the Space Functions found in the American Ingalls' Tables. This is an extremely laborious process and is shown for interest sake and because it permits comparison with values of C computed using computer programs which calculates retardation and C directly from input values for V, v & the distance, d, that the bullet travels between the chronographs measuring these velocities. In this instance, a program, #PBCv, using the British 1902-9 functions, for Retardation of the Standard Projectile, was used to perform the calculations.

The 20 graphs, (some of them examples, perhaps, of what not to do with trend-lines & their equations) are viewable in the economical .gif format. You should be able to load the data from the tables into an application on your computer in order to manipulate it and produce your own graphs. Here are some pointers to a few of the graphs. Graph 15 shows a plot of Ballistic Coefficient over Final Velocity (which is the velocity measured on the chronograph furthest form the firing point). Note the very high value of C just above the velocity of sound. It is almost as though the bullet was forced to travel faster so that it would not break the sound barrier! The velocity of sound being close to 1120 feet per second in these tests. At what point the retardation of the projectile was affected by its approach to the velocity of sound, it is impossible to say. Its retardation could be constant, determined by its starting velocity, or it could be that it decelerates less near 1120 fps. We need to place more chronographs in the firing line! Who's up for it? Projectiles which just become subsonic, seem to suffer from increased retardation, having lower values of C. Retardation at many velocities is clearly not explained by a simple, to us, series of 7 equations used in the attempts to explain the retardation of those early Standard Projectiles. ( If you plot the results of the G‚vre (G1 Projectile) firings, how many & what functions, for which velocity ranges, might you use to calculate R for that Standard Projectile? ) The military have doubtless conducted extensive firings of projectiles of interest to them, unfortunately, for the science of ballistics, most such organizations are reluctant to make their ballistic research public. Graph 4 shows Initial Velocity over Final Velocity, being remarkably linear overall but with some noticeable anomalies. Graph 9 is a plot of the Retardation of the Standard Projectile, R, over the retardation of the Test Projectile, r. Notice here how a 'canyon' is formed by bullets which have very markedly different retardation values, r, where the Standard Projectile retardation values, R, remain much the same. Only those bullets with final velocities very close to the velocity of sound are found within this gap. This may be more obvious in Graph 6, where R is on the longer, X axis. Graphs, 18, 19 & 20, of retardation, r, over velocity also seem to point to the existence of velocity 'no-go areas', which result in a range of retardation rates for projectiles traveling at essentially similar velocities. The similarity in the pattern of points, in graphs 5, 6 and graphs 18 thru' 20, clearly demonstrate the extent to which R is a function of velocity. Others may interpret some of these results in different ways, hopefully someone can explain them? Can these results be reproduced for other projectiles? Is there some harmonic of the velocity of sound responsible for anomalies at other velocities? What happens at twice or three times the velocity of sound? Can you help to increase the body of knowledge in any of these areas?

9mm 125LRN Graphs: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.