[opsboss]

I was recently reading Life and Adventures of “Billy” Dixon, as compiled by Frederick S. Barde (available online at http://texashistory.unt.edu/permalink/meta-pth-29402:1 (http://texashistory.unt.edu/permalink/meta-pth-29402:1) if you’re interested), and got to thinking about the famous shot.

Rifle: Sharps .50/90 (big "50")
Bullet: 500-grain LRNFP
Muzzle Velocity: 1420 fps
Ballistic Coefficient: .277
Range: 1538 yards

Question: What was the holdover? (In feet, to the nearest foot.)

First one with the right answer gets this month's Trigonometry Gold Star.

Best, Ops

[KD5NRH]

Rifle: Sharps .50/90 (big "50")
Bullet: 500-grain LRNFP
Muzzle Velocity: 1420 fps
Ballistic Coefficient: .277
Range: 1538 yards

Question: What was the holdover? (In feet, to the nearest foot.)

What was the temperature, barometric pressure, relative humidity, zero range, and the height of the sights above the bore axis?

At that range, they're all very relevant. With a >5s flight time and the total drop at that range, winds somewhat above ground level become a factor too.

I'd post the answer based on some reasonable assumptions for those factors, but the credit would have to go to the guy that wrote the ballistic calculator software I used.

EDIT TO ADD: I'd also have to look at the original site to believe the accuracy of that distance, given several later revisions:
http://findarticles.com/p/articles/mi_m0BQY/is_6_51/ai_n13781619/pg_2?tag=artBody;col1
Even if Billy Dixon did shoot an Indian off a horse at long range it almost certainly was not at 1,538 yards. Billy Dixon himself never said so. On the third day, the story goes, after the battle a small group of horseback Indians exposed themselves on a distant butte, and Billy Dixon rested his borrowed Big .50 Sharps and dropped one of them. Supposedly, some years later Dixon related this story to his wife Olive K. Dixon who then included a single paragraph about it in her book The Life and Adventures of Billy Dixon, published after his death in 1913. In the first edition (1914) of that book the distance is said to be 1,200 yards. According to Adobe Walls; the History and Archeology of the 1874 Trading Post by T. Lindsay Baker and Billy R. Harrison, a Texas surveyor measured the range in 1924 and determined it was 1,028 yards. The second edition of Olive K. Dixon's book published in 1928 changed the range to 1,538 yards.
Besides, the documentation about the Adobe Walls battle mentions several impressive shots made on groups of Indians at extreme range by several of the white participants. It is strange that just one shot has been singled out above all others. If you go to Adobe Walls today equipped with a rangefinder you will quickly see that none of the distant buttes are 1,538 yards away. One is about 600 yards, and the other is about 1,200 yards.

[7.62mmFMJ]

Too early for a physics problem :D

It is definitely indirect fire.

[OFallon]

32'9.75"

[opsboss]

What was the temperature, barometric pressure, relative humidity, zero range, and the height of the sights above the bore axis?
Well of course all those factors do have an influence. Indeed, a significant influence. And most of them we simply don’t know. But there are weather almanacs and topo maps available, and rifle specs, so one can look them up and take a “best guess.”

With Dixon’s reputation as a crack shot, my assumption was that he knew (more or less) what the maximum zero (sight) range on his rifle was; having probably taken a few shots at max elevation on his Creedmore tang sight during some lazy afternoon when he had nothing better to do. And, though he probably had little understanding (if any) of the math involved, he likely knew that temperature and elevation did affect trajectory.

Here’s how I approached it. The maximum elevation on a typical long-range Creedmore sight is 3”, and I’m guessing the sight radius is about 38” (which seems about right for a tang-mounted sight on a 32” barreled Sharps). Using a little trig, that results in a maximum launch angle of 4.523° (assuming he used the sights, which seems reasonable as he stated, "he took careful aim"). The elevation in the Canadian River valley in Hutchinson County is around 3,000’. According to the almanac, temperatures on June 27 run, on average, between 64° and 90°. Now I’ve not seen anything that specifies the time of day for Dixon’s shot, but as I noted earlier, he probably knew that he’d have a bit more drop in the cool morning than the hot afternoon. So I arbitrarily picked 70° (mid-morning), and called it “good enough.”

So, at standard barometric pressure for 3,000’ (26.42”), 70°, ballistics as given, and a launch angle of 4.523°, zero range would have been about 1466 yards. Thus, making the shot would require a holdover of about 28.5 feet, assuming a 1.25" height on the front sight (the sight height really only making a very small --- inch or two --- difference).

Now, though I think it’s a bit cool for Adobe Walls that time of year, if one bases their calculations on standard temperature, 59°, rather than my assumption of 70°, maximum zero range becomes 1456 yards, and the holdover is 32.8’.


:winner:

Paul!

Well done! :clap:

Best, Ops

[wadcutter]

It was a lucky shot. ;)

[opsboss]

It was a lucky shot. ;)
Sure it was. Even Dixon said so.

Still, we make our own luck.

Best, Ops

[wadcutter]

Sure it was. Even Dixon said so.

Still, we make our own luck.

Best, Ops


Yes indeed.

It would be fun to try and re-create that shot!

[Birchwood]

Yes indeed.

It would be fun to try and re-create that shot!
IIRC, Venturino did it. Took some computer guys along, same/similiar rifle.. compulated and eventually postulated the results.

They probably used satellites..;)

Birchwood

[KD5NRH]

:winner:

Paul!

Well done! :clap:

Now what was the energy at impact, in furlong-carats? :D

[wadcutter]

Was he shooting bullets or boolets?

[StrawHat]

With Dixon’s reputation as a crack shot, my assumption was that he knew (more or less) what the maximum zero (sight) range on his rifle was; Best, Ops

In fact, it wasn't his gun but a borrowed rifle.

Curious shot, none the less.

Does any one recall reading about another long shot made by a rifleman of that era? The details, as I recall them, were similar in that it was an Indian attack but on a group of soldiers and the scout was able to connect with a lone mounted Indian at something around 1400 or 1500 yards. He called the shot, the Indian fell, and the attack was over. He, like Dixon, claimed it a chance or scratch shot.

I don't recall the rest of the details but it was recounted on Paul Harvey.

[StrawHat]

Was he shooting bullets or boolets?

Most likely, cast lead.

[opsboss]

In fact, it wasn't his gun but a borrowed rifle.
True, but Dixon was certainly familiar with both rifle and cartridge. His own “Big Fifty” was lost but a few days earlier when his wagon sank in quicksand while fording the Canadian River. Further, as Sharps had introduced the .50/90 only about a year and a half before Adobe Walls, it stands to reason that one Sharps .50/90 was pretty much like the next.

Additionally, it’s not as though he borrowed the gun for just that shot. He got it “early in the fight,” as he puts it, and “was making considerable noise with it.”


Now what was the energy at impact, in furlong-carats? :D

Furlong-carats, huh? And this would be for the benefit of disgruntled horse racing fans using diamond bullets at Churchill Downs?

Anyway, troy or metric carats? Eh, let’s use troy, makes the conversion a bit easier.

Well, let’s see… 2213 carats to the pound, 7000 grains to the pound, so 3.164 grains/carat. And, 660 feet in a furlong, so…

Let’s see, uh, the gravity constant becomes (32.2/660) = 0.0488 furlong/sec*sec, so mass becomes, 500 * 3.164 * 0.0488 = 3239 carat/sec*sec/furlongs.

(Too bad the vB editor doesn't handle superscripts.)

Velocity is 594 ft/sec or 0.9 furlongs/sec, so kinetic energy is…

0.5 * 3239 * (0.9 * 0.9) = 1312 furlong-carats.

Or, doing it the simpler, but slightly less precise way, 392 lb/ft * ((2213 carats/lb) / (660 feet/furlong)) = 1314 carat/furlongs.

That sound about right?

Best, Ops

[Frank V]

I'm not sure of the yardage, I think it was probably a combination of a very skilled shooter, a good measure of luck, good on Dixons part & bad on the Indians part, & just maybe that sixth sence that some shooters aquire of this is just right. I think it was Elmer Keith that said with enough practice impossible shots become somewhat more common. Thanks Frank

[KD5NRH]

0.5 * 3239 * (0.9 * 0.9) = 1312 furlong-carats.

I guess my numbers are on the laptop, but that seems close to what I remember coming up with.

This sort of thing was how I taught one of my teachers in HS not to just say that we could give an answer in any units we wanted to.

[Stevejet]

You forgot to carry the pi. And pie are round, not squared!

[2quads]

This stuff makes my head hurt.