Minie-Ball and its Parabolic Trajectory

The Minie ball, the bullet most identify as the weapon of mass destruction in the civil war, bears the name of French Army Captain Claude -Etienne Minie. He is generally credited with solving the problem of using expanding gasses to force portions of the bullet into the rifle groves. Others improved upon his design.

Amongst other attributes in the minie-ball’s design are the unique rings formed into the body below the conical shaped head. These rings accomplished two tasks: first to minimize friction within the bore of the rifle musket and second to provide guidance once in flight. The cylindrical shape is a departure from the previous musket bullet – the ball. This shape allowed the minie-ball to exit the bore of the rifle musket tube in a linear fashion. The design of the base allowed the gasses, derived from the explosion of the 60 grams of gun powder, to force the bottom end of the bullet into the rifle groves in order to spin. This spin tended to improve the accuracy of the bullet, much the same as a quarterback throws a football. The second element to improve guidance is the rings. These corrected any tendency of the bullet to wobble in flight. This was accomplished by increasing the resistance to air flow if one portion of the bullet were to yaw left or right along the flight path of the bullet. The bullet would be forced back to where the resistance in the air was minimized. See C. Wilcox, p. 130-134 for a more technical explanation

This innovation, use of the rings, was discarded soon after the civil war because it substantially increased air resistance and contributed to its reduction in range and the shape of its trajectory – the parabolic arc. The minie-ball, due to its relatively low muzzle velocity, was more pronounced the farther one attempted to shoot. This natural phenomenon is due to gravity. Air resistance means the bullet flies slower and gravity pulls it down. Jack Coggins in his book Arms Equipment of the Civil War, drew the bullet path as follows, likening it to a rainbow.


More precisely, the tail end of its flight is a more pronounced, downward path and therefore shorter. From this diagram, you can see that the dangerous space as Wilcox termed it occurs at the beginning and end points of the bullets’ flight path.
For my purposes, this will alter what I termed the danger zone. One of the first clear models of this was a blog by 67thtigers.
His drawing, reproduced below demonstrates the high parabolic arc of the minie-ball.

Parabolic-arc-67tiger-blog-webIn this graph, ground is in light blue at the bottom. The purple horizontal line represents the height of the top of one’s head. The musket rifle is aimed at three different ranges; 100 yards, 300 yards, and 500 yards. These coincide with the three preset sight apertures provided on the Springfield rifle musket. The height in inches, relative to the firers’ muzzle, is provided along the left axis. It is easy to appreciate the challenges to a civil war soldier hitting his target. Doc White described the problem this way.
“Firing at a target 225 yards away with a Springfield is difficult; you must set your sights at 300 yards, and then aim below the targets feet, awkward when poorly trained soldiers naturally shoot high. The solution adopted for the line infantry of the US, CS and also most of continental Europe was to set sights at 100 yards, and only shoot at 150 yards or less”.
Given this understanding of the problem of the parabolic arc, I searched for software that would assist me in plotting the impact in the swale as experienced by both confederate and union soldiers during the battle of Fredericksburg in December 1862.

My next blog will show the results.

About Peter Glyer

I am retired with a lifelong interest in history, primarily the Civil War and WWII - Europe. I was an Army engineer, hence my interest in terrain. I graduated with a degree in City and Regional Planning and a Masters in International Relations.
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6 Responses to Minie-Ball and its Parabolic Trajectory

  1. Pingback: THE MINIÉ BALL | Weapons and Warfare

  2. J. Go. says:

    I just noticed your previous article addressed the topic of weapons nomenclature re; muskets vz rifle muskets. Sorry about that.


  3. J. Go. says:

    I’m sorry but, you really don’t seem to know what you are talking about, at least concerning bullets and shooting. You are making a number of errors.
    First of all, the Minie’ Ball is not cylindrical- it is conical. The US and some CSA versions had 2 or 3 grease rings around the base.
    Secondly, the ring grooves in the Minie bullet’s base primary function then, and now, were/are to hold grease. The grease served multiple purposes; lubrication, preventing leading, and keeping fouling soft for easier reloading & cleaning. I don’t know where you got that bit about the rings stabilizing the bullet. I’ll stop short of calling it nonsense but I have surely never heard of such a thing in 40 years of muzzle loading shooting. The English Pritchett bullet, a form frequently used by the Confederates, was designed for the English P1853 rifle musket (used by both sides) well known for its accuracy. It had smooth sides with no rings and utilized a greased paper patch to grip the rifling and lube the bore/fouling. You might look at the many bullet types represented here-
    Another thing- as for the rings being [quote]”discarded soon after the civil war”[end quote], that IS nonsense. The primary US military cartridge after the Civil War was the 50/70 Springfield until 1873 when the 45/70 was adopted. It remained in service until the 30 caliber cartridge was adopted in 1903. The lead bullets for those cartridges were ring grooved and greased. Grease grooves are still frequently used on bullets yet today and still for the same purpose.
    The rifle* muskets used in the Civil War, though many and varied, were primarily represented by the US Springfield and English made Enfield. The P1853 Enfield in particular was known for it’s accuracy, was sighted to 900 yards and many kills were made at ranges exceeding 500 yards.
    Another thing and this will affect your further analyses of the impact (figurative) of shooting into the swale. There is a problem encountered when shooting at vertical angles either above or below the horizontal plane that causes the bullet’s point of impact to hit high. When shooting up- or down-hill, you have to hold your sights below the target in order to hit the target.
    Yet another point calls for conjecture (for either of us). You make reference to “poorly trained soldiers.” Keep in mind that many of the Confederate soldiers were experienced marksmen before entering service. Keep in mind too, that the average Confederate soldier that day was a veteran of many battles. One more consideration for you is that the best shots were crowded up to the stone wall with the men behind loading weapons and passing them forward to the marksmen. That would have rendered an above average rate of concentrated fire of better than average accuracy.
    Another thing you are not taking into consideration I think. The front sight blades of the rifle muskets then in use were fairly large. At longer ranges, they blank out a target of an individual soldier. What the soldiers did then was to target the mass of an enemy’s battle line rather than individuals. The effect was no less devastating.
    I wonder… Are you a shooter? Have you ever fired a rifle musket? If not, I suggest it. It will change your perspective on this subject.
    As a final thought here, I have referred to the weapons used as “rifle muskets.” This term is accurate enough though the Springfield might be considered a “rifled musket” as opposed to a “rifle musket.” A “rifle musket” will maintain accuracy or more to the point consistency, longer than a rifled musket’s thinner barrel walls.
    I’ll wrap it up now. I hope you find it of interest and hopefully at least, some benefit. I look forward to looking over your other pages.


    • Peter Glyer says:

      Thank you for your comments. I will answer them in roughly the same order as you raised them. I noted the Minie was both conical and cylindrical. My text deals with both aspects in turn, including a period drawing of the Minie itself. I believe we are saying the same thing.

      I was remiss for not also noting the grease and its function. I also managed to misspell Pritchett in the previous blog. My main point for citing the course correction aspect of the grooves relates in part to the book that our friend Cadmus Wilcox wrote prior to the civil war [see citation on blog]. This is where the cylindrical portion of the bullet comes into play vs a ball. I was really attempting to stress how the Minie cone and cylinder combined was more accurate than a ball. Lastly, I guess my mindset was that with the advent of breech loading rifles, the Minie of civil war use quickly vanished into the shadow of history.

      The issue of the distance at which an Enfield or Springfield could hit a target appears from recent literature to be a moot point. Early pre-civil war authors like Wilcox and a slew of others expected the Napoleonic style battlefield to be turned on its ear so to speak. Artillery and cavalry were to have met their match with the rifle musket and its extended max range. Quite the opposite seems to be true. Authors such as Paddy Griffith, Earl Hess and Brent Nosworthy, to name a few, were quite astounded when they analyzed the engagement ranges of civil war infantry. They found only a slight increase in distance over the older smooth-bore muskets. Individual marksmen may well have sniped or skirmished at greater distances. Line infantry seem to have preferred much shorter ranges at which to bring devastating fire. Confederates at the wall on the Sunken Road were restrained by their officers before they opened fire.

      The issue of poorly trained soldiers is also one that receives some press from my four authors. Wilcox devised an entire system to train the soldier on estimating ranges. The other three talk about how infantrymen were never adequately trained. Backwoods boys and farmers aside, few units seem to have rigorously trained on rifle ranges, let alone worked on estimating range. I realize you have a strong bias towards your Texans. Some units and individuals did exceed the norm. I did not see convincing literature that led me to understand differently. This includes unit histories, diaries and more modern investigations. Accuracy was also questionable given the necessity of having to completely reset the sight-picture every time one loaded the weapon or was handed a replacement which was fully loaded under the pressure of maintaining a high volume of fire.

      While I have never fired a rifle musket, thanks to Uncle Sam, I have spent a lot of time on army rifle and pistol ranges. The oldest weapon was an M-1 in the mid-60’s, M-14’s and 16’s in the 70’s, 80’s, and 90’s to include a quick time attempting to qualify with a German assault rifle in the early 70’s while stationed in Germany in a combat engineer unit.
      I agree with Earl Hess when differentiating the weapon. I chose to use the term rifle musket rather than rifled musket. The former denotes a weapon that had spiral grooves inserted during the initial manufacture. The later had the rifling inscribed after the initial manufacture when the warring parties attempted to retrofit their smooth-bore muskets.


      • J. Go. says:

        Good reply and I apologize for being a little, OK, maybe -more- than a “little” harsh. Too often I see comments on things by people who really are clueless or have not done done any appreciable homework. I am happy to say that is clearly not the case with you. There is simply too much information, much of it biased, to know much of any single part of this conflict without a lifetime of study. (Which to some extent, I have done. I used to correct my history teachers in high school- with references of course.) There is always room for debate.

        Concerning the marksmanship of some units that is true. At 2nd Manassas the 5th Texas met the 5th NY. As it happens, the previous winter quarters found the two units opposite each other and many were the jibes and taunts between pickets as to what would come from their meeting in battle. The issue was settled firmly once and for all. The 5th NY fired several volley’s against the approach of the 5th Texas. Total result being about 23 casualties (Simpson- Hood’s Texas Brigade; Lee’s Grenadier Guards) The first volley of the Texans, admittedly at point blank range, finished the 5th NY. It was said you could walk their line position end to end w/out touching earth so closely the bodies lay. The few survivors ran for it. On the flip side, at Sharpsburg the previous fall the 1st Texas earned the sad title of the highest Reg’t loss in a single day’s fighting- 81%- at the hands of another sharpshooting outfit- the Pennsylvania “bucktails.” Now, the actual numbers were not so great because the 1st Texas was somewhat heavily reduced by the summer’s campaigning. Some give that highest loss rate to the 5th NY based on the actual numbers I believe. Their percentile was more like 75%. Take your pick.
        As for the training issue, that varied during the war. I would say the Confederate army maintained a higher accuracy rate since her few replacements tended to be merged into veteran units whereas the North tended to keep forming new units grouping the untrained together. One might consider combat accuracy by Spottsylvania’s tree. As big around as a man, the tree was shot down at waist to torso height by rifle fire. Standing up on that field was a bad idea.

        Gotta run. More later.


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