Bullet trajectory

[Pritchett Ball]

The Rifle Musket in civil War Combat by Earl J. Hess

"Another, related problem that affected fire effectiveness lay in the parabolic trajectory of the rifle musket. Because of its high arc, the Minié ball created a huge safety zone for the enemy during much of its flight through the air. This problem was most pronounced when firing at distant targets, but this sort of long-distance firing was the key difference between the rifle musket and the old smoothbore weapon. It was incredibly difficult for the average soldier to compensate for the unusual trajectory and make his shots count at ranges longer than about 100 yards. This greatly decreased the effect of the rifle musket precisely in the area where advocates though it might have a revolutionary impact on warfare.
A rifle musket sighted for 300 yards could be deadly at short range, but after about 75 yards the bullet sailed above the height of an average man. The next danger zone lay at the far end of the trajectory, the last 110 yards (about 240 to 350 yards from the shooter). In this last danger zone, the target could be hit at any height along his body, depending on where in the zone he happened to be when the bullet made contact. For the rest, fully 115 yards of the bullet’s flight, only 185 out of 300 yards of the bullet’s journey constituted a danger zone to the enemy."

If I understand correctly, the bullet NEVER goes ABOVE the line of the muzzle, starting to drop soon after it leaves the barrel. So, the muzzle would have to be pointed up at a degree of angle that would allow the bullet to land or hit at the 300 yard range. Knowing the trajectory is like a thrown rock, I'm just not willing to be a Guinea Pig in testing out this theory!

So, is there something wrong with Hess's conclusions here? I'm having a hard time understanding what he is saying.

Kevin Dally

[dixieflyer]

Re: Bullet trajectory

Kevin,
You are right, a projectile starts to fall immediately after leaving the barrel of any firearm, ergo you have adjustable sights to compensate for that. I well remember an article in my youth that stated if you wanted to sight in a 30-06 at 100 yards and you wanted to save some footwork, you could place the target at 25 yards (where the bullet first crosses the LOS) and it pretty much have it dead on for 100 yards. Here is a link with a graphic (scroll down to see it)

http://www.hornady.com/ballistics-resource/external

While this is a modern application, the same physics apply.

I hope this helps.

[Pritchett Ball]

Re: Bullet trajectory

Warren:

I think the author should have placed an actual graph, (like the Hornady info you linked) explaining his theory.

I know shooting an original 1863 at a 480 yard distant full size sheet metal target of a Buffalo, that 500yard site raises the muzzle up a good angle! Someone reading what the author is saying would seem to think the muzzle is level, and the bullet flies straight till about 75yds, and THEN rises above a man at 75yds...not correct.

Is that what the author is saying?

Kevin Dally

[Curt Schmidt]

Re: Bullet trajectory

Hallo!

There are formuale in physics that calculate these things out. But, in brief...

Think of holding a rifle parallel to the ground. The bullet starts to be pulled down by gravity as so as it leaves the muzzle.
To increase the "range" (how far it travels before striking the ground), one has to increase the angle of elevation or increase the velocity, or both.

To borrow the old "Coggins" example...

If a man is kneeling with his rifle muzzle 40 inches above the ground... sighting at the belt plate of a enemy at 300 yards:

at 50 yards the ball would pass over the head of an average man, and rise in its arc ascent and descent to pass over the head of a man at 250 yards to strike the man in the belt plate at 300 yards, or go oneto hit the feet of a man at 350 yards.

If the shooter misjudged the distance by say 50 yards one way or the other, he would miss.

To help a soldier gauge the sight adjustments for the distance, a "typlcal" rifle or rifle-musket with "short range" rear sights had 100-300-500 yard adjustments, while the "long range" rear sights went in 100 yard jumps to 900 or 1000 yards say.

But, if i understand your statement correctly... while teh bulelt never reallr ises above the barrel line... to extend range the rear of the barel keeps getting lowered so while the "line" is okay, the parabola or trajectory of the bullet goes higher and higher. (Until the energy imparted to the ball by the charge and its ballistic issues with air, wind, and temperature fails to keep it airborne and it "falls" to the ground.)

Of course, the side discussion is how practiced and experienced a soldier was in assessing distances, or firing a distances other than rear sights were graduated to. Plus all of the other stuff about combat such as discipline, experience, nerves, haste, snap shooting, jerking, or flinching, etc., etc.

The pesky thing IMHO, and a question I missed in high school physics is that if you drop a another bullet at the muzzle, at the same time the bullet leaves
the muzzle... both bullets hit the ground at the same time.
My flawed thinking was that gravity pulled the dropped bullet at the set rate, while the horizontal "momentum" imparted to the fired bullet by its speed and velocity kept it "airborn" longer.

It doesnt.

The trajectories of round balls and Minie balls is why advancing formations were if possible, "ideally" spaced or distanced in waves in the attack so that high bullets passing over one "line" would strike the ground between lines rather than striking the line to the rear.

Oh, IIRC, an M1 Garand set with 300 yards, would have its bullet about seven (7-something) inches above the line of sight at 150 yards.

Curt

[dixieflyer]

Re: Bullet trajectory

As usual, Curt answered this more eloquently than I did. :)

[Pritchett Ball]

Re: Bullet trajectory

It is interesting to see that a .580", 405gr. target minie bullet will strike high at 50yd, when it's sighted in dead on at 100...

The attached photo is of a 3" round dot I shot 5 times at 50yd, with a load that impacts dead on at 100yd.
As you can see, it's several inches high at 50yd, would have continued on till impacting on target at 100yd. The load was a .580" Hodgdon minie ball, at 405gr, with 38.8 gr of FFFg powder. this load is real accurate out to 100yd in my 61 ArmiSport Enfield.

I appreciate all the responses!

Kevin Dally

[Curt Schmidt]

Re: Bullet trajectory

Hallo!

"It is interesting to see that a .580", 405gr. target minie bullet will strike high at 50yd, when it's sighted in dead on at 100..."

Which is why one can NUG identify an N-SSA competition longarm as it is necessaey to either lower the rear sight or raise the front. Many/most times, one is limited to how much lower the rear sight can be lowered, so the option is to add a higher front sight blade to lower the group. (The visual here being that with a higher front sight, one is not raising the muzzle as high because the higher front sight gets their "first" to make the sight picture alignment.)

I don't remember the equation from geometry, but the rear sight, front sight, and the bore center line are essentially a very long "lopsided" triangle. With a milling machine or something capable of precise mathematical changes, one can compute the rise or fall at the POI by precisely adding/subtracting the adjustment of the height of the one teeny tiny side of the VERY long triangle.

Being brief, the sight radius and heights were "set" by the gun designer as part of the "design" so that the sights would be set for the graduated scale or aperature.

Curt

[Pvt_Sullivan]

Ballistics

For the unanswered questions raised by the earlier poster pointing out that his 1861 Springfield always hit high at 50 yards when it was sighted for 100 yards.

First you need an understanding of ballistics. Here is an image that shows a bullet's path from the muzzle to impact, click on the picture for the webpage with more detailed instruction.



As you can see in the picture the barrel is not perfectly parallel to the alignment of the rear and front sights. This is done to compensate for the forces of gravity and drag that act on a projectile during it's flight. The purpose of weapon's design, especially for standard service weapons ment to be used by newly trained line troops is to set the sights for the effective range of the weapon. This is done so that by applying basic marksmanship techniques, the point of impact at the effective range is within the critical zone of the target.

Partly this doesn't have much to do with Campaigning since we don't carry live rounds, nor did the average soldier have detailed knowledge of these principles.

The country boys who did know how to shoot, would have a much more practical knowledge of changing their point of aim based on the distance to their target. They would instinctly know to lower their point of aim for a target close to them and to raise their point of aim for a target at distance. Then as well they understand the affect of wind as well as target movement in adjusting their point of aim.

Now many of the original cast in 1861 and especially those from the urban centers of the country had no experience with a fire arm beyond the pocket pistols and derringers of the day used for personal protection. They were trained by the armies to load and fire their pieces when ordered and anything they picked up about marksmanship was more by accident and experimentation than actual training.

SO, in my opinion although an interesting topic... there is limited application to Authentic Campaigning. If you want to shoot your piece with live rounds at a target go get into the NSSA and enjoy that hobby.

[AndrewGrim]

Re: Ballistics

Thanks for sharing. I know the same elevating of the barrel principles are also used for most artillery.

[Mississippian]

Re: Bullet trajectory

Pete,

There was some marksmanship training in the AoT in early 1864 while at Dalton. The soldiers got to fire a few rounds at a target and then had to go out and get the lead. This included the artillery. I want to say the sharpshooter units and ad hoc sharpshooter battalions got pretty regular practice

Will MacDonald

[Pvt_Sullivan]

Re: Bullet trajectory

Pete,

There was some marksmanship training in the AoT in early 1864 while at Dalton. The soldiers got to fire a few rounds at a target and then had to go out and get the lead. This included the artillery. I want to say the sharpshooter units and ad hoc sharpshooter battalions got pretty regular practice

Will MacDonald

Will, I would never doubt the pearls of wisdom you find in the historic record. In my opinion that reference does make my point that target practice and marksmanship training was more aberration than standard operating procedure.