Using Sight Picture to Adjust Bullet Impact

It is not enough to simply align the sights of a rifle on the target and expect to get a hit, especially with black-powder ammunition, which was both slower than modern ammunition and more susceptible to the wind.  In this essay we will consider ways to use the sights of Nineteenth-century military rifles in order to ensure consistent, accurate shooting at various ranges and in varying wind conditions.

Elevation

Most British military rifles of the Nineteenth Century had rear sights which were adjustable in 100-yard increments from 100 to 900-plus yards and were zeroed to hit a target three feet above the ground at the set range.  Soldiers were taught to carefully estimate the range to the target and then to set their sights to be able to correctly engage targets at the estimated range.

This was crucially important because of the rainbow-like trajectory of black-powder ammunition.  For example, when firing the Snider-Enfield rifle at 300 yards using the 300-yard sight setting the bullet trajectory had a maximum height of seven feet above the ground; the bullet would hit a man-sized target in the head at 220 yards and the feet at 355 yards.  Thus, when aiming at a target's waist using the 300-yard setting on the rear sight, the "danger zone" in which an infantryman would be hit somewhere between the head and feet was only 135 yards in width, so the shooter had to estimate the distance to within 135 yards of the actual distance.  The farther the target, the smaller the danger zone, and at 600 yards, for example, the danger zone was only 30 yards wide and the maximum height of the bullet's trajectory would be 23 feet above the ground.  For more about the characteristics of the Snider rifle, see here.  For a comparison of the ballistics of the Snider-Enfield rifle to the Martini-Henry rifle, see here.

Each individual rifle was somewhat different, of course, and so a shooter had to know his own piece and whether it shot somewhat above or below that standard.  Moreover, if the estimated range fell between the round numbers for which the sights were set (at, for example, 225 yards, or 350 yards), it was helpful to be able to adjust one's point of aim in order to try to get in the middle of the danger zone in order to make for the highest likelihood of a hit.  Soldiers were taught to place the front sight post halfway between the bottom of the notch and the top edge of the rear sight during normal shooting; this was called "half-sight" (see the picture below).

Half-sight picture from the 1870 Musketry Instructions, p. 35.

In addition, the very tip of the front sight could be aligned with the bottom of the notch for "fine sight" or the front sight could be aligned with the top edge of the rear sight for "full sight."  Shooters today are all taught to use "full sight," however, as this shows, that was not the case in the Nineteenth Century.

The 1870 Musketry Manual tells us:  "As the two methods of aiming first named cause a slight difference in the angle of elevation, it is necessary the recruit should understand that the ordinary rules for aiming are intended to apply to the half-sight, and that as some of the rifle may carry high and others low, allowance must be made for such defects, by aiming with fine-sight when the rifle carries high, and with full-sight when it carries low." (id.).

In addition, the shooter can also select a slightly higher or lower point of aim to change the point of impact.  There are three choices here, a "six-o'clock hold," a "center hold," or a "twelve-o'clock hold," which represent respectively aiming below the center of the target, at the center of the target, or above the center of the target.  While this is often thought of as applying strictly to target shooting, it can apply in a military context, too.  Soldiers were taught to shoot at the belt line on opposing infantry, however, the shooter could hold at his target's knee line for a six o'clock hold or shoulder line for a twelve o'clock hold.

Thus, there are a total of nine different sight pictures which the soldier can take in order to adjust his aim to allow for "in between" ranges in a consistent, repeatable manner.  Those nine sight pictures are represented in the diagrams below.  Note that in these illustrations the half-sight is called "medium."  Unfortunately, these sight pictures are matters of estimation and will vary from rifle to rifle, so the shooter has to practice using them in order to be able to judge just how much effect each of the different sight pictures will produce with his particular rifle and ammunition.

Windage

With regard to windage, most of the musketry manuals are not very precise, and the sights on military rifles of the period did not have any mechanical means of adjusting for windage.  Retuning to the 1870 Musketry Manual, we are told:
"As no fixed rule can be laid down to guide the soldier he must acquire experience as to the amount of allowance he should make for wind, in carrying his rifle to the side from which it is blowing, or in giving his rifle a little more or less elevation, but always taking into consideration two things, the strength of the wind and the distance of the object at which he is firing, since on the latter will depend the length of time the wind will have to act. He should also watch the effect of his shot, and make more or less allowance as he finds necessary; and he should bear in mind, that the effect of a wind from the front or rear is much less than that of a side wind which acts on a larger surface of the bullet." (p. 37).

Other sources, however, address the question in more detail.  In The Rifle Shot's Manual of Target Shooting, the anonymous author ("A. Shooting Man") gives detailed information about how wind of varying strengths and blowing from different directions affects the path of a bullet (see pp. 83-85).  He then goes on to say that the slider on the rear sight assembly can be removed and replaced upside down so that the straight edge  of the bottom of the slider is used rather than the V notch in normal use, and suggests placing marks on this to align with the front sight post (which would make most of the sight picture choices above impossible) to allow for windage.
"In allowing for winds there is a marked advantage in using the flat bar of the slider of the backsight as a wind-gauge, as it must be evident to every one that better shooting can be secured when aiming dead on or near the bull's-eye, than when aiming quite away from it; but, in order to meet the views of those who prefer the V to the straight bar, the allowance will be quoted for both systems." (Anonymous, The Rifle Shot's Manual of Target Shooting. London:  William Clowes and Sons, 1876. p. 90).

The flat bar of the rear sight used to allow for windage.  The small point above the line is the front sight, the horizontal line is the edge of the slider, and the vertical line in the middle of the slider is a mark made by the shooter. This picture represents the sight picture for a "light" wind from the left. p. 93.

The author then goes on to say that the front sight post should be aligned with the target and the rifle moved so that the penciled center line was off from the front sight post, as in the picture above, by an amount which, in the shooter's estimation, would allow for the wind.  He says that for a light wind, the sight should be over a spot one-third of the way from the center line to the edge; for a medium wind it should be halfway between the center line and the edge, and for a heavy wind it should be two-thirds of the way from the center line.  Obviously, these are vey imprecise guides and would have to be determined by experimentation.

The 1879 Musketry Manual for the Martini-Henry Rifle has a supplementary section on "practice" shooting ("Part VI").  In it, this same idea of switching the slider on the rear sight leaf is described, although no specifics of its use are given:  "192. When firing with the leaf of the backsight raised the soldier may use either the notch or the level edge slide, which will be reversed by the armourer as necessary." (p. 250).  It says in an earlier paragraph that marks may be made on the sight if desired:  "188. Temporary marks on the slide with pencil or any substance that can be easily effaced may be permitted." (id.).  It is not clear, however, how often troops actually used this technique, either in practice or in battle.

The Rifle Shot's Manual also shows how to adjust for wind when using the V notch side of the sight.  He says to align the center of the front sight post with the right or left edge of the V notch (depending upon wind direction) with the shoulder of the front sigh post aligned with the center of the V notch, as in the figure below.  The shooter can then align the shoulder of the front sight post with the center, right, or left of his target to increase the windage even more; in the picture below, we see a six-o'clock hold (of the edge of the front sigh post, not the point) on the far left of the target.  To use this in combat, the shooter could align the shoulder of his sight on either side of his enemy's body rather than in the middle.  This seems a more practical approach to allowing for the wind since it does not require disassembly of the rear sight.  Obviously, this approach can be used with the nine sight pictures shown above.

Using the V notch of the rear sight to allow for wind.  Rifle Shot's Manual p. 40.

The rear sight of my Mark IV Martini Henry.  It is extremely hard to see, however, there are very light lines scored down the center of the slider as well as halfway to the edge on either side of the center.  It seems likely that these marks were used for windage sighting as discussed above.

Conclusion

It is becoming fashionable among modern authors to discount early black-powder rifles for the simple reason that soldiers in the American Civil War were incapable of using rifled muskets to their full potential, which led to battles in that war being fought at ranges similar to those seen in earlier wars fought with smooth-bore muskets.  In fact, however, when rifles were used by troops carefully and thoroughly trained in their use they were capable of stunning feats of long-range accuracy, as the 93rd Highlanders of the famous "thin red line" (actually, it was the "thin red smear tipped with steel") proved against the Russian cavalry at Balaclava.  Doing so, however, required soldiers to be well trained in both the principles of ballistics and the mechanical aspects of their weapons, and the School of Musketry at Hythe gave British soldiers training in both.  In this brief essay we have examined some of the techniques for using the sights of Nineteenth-century military rifles to achieve long-range accuracy.  This is not the whole of musketry, but only an analysis of how to us the sights for consistent and accurate shooting taking into account wind and elevation.