Structured barrels are a relatively recent development and interesting in and of themselves. One of the main objectives is to eliminate barrel harmonics that distort accuracy. The article didn't provide much info on the structured barrel used to break the record, so here's some from the only company I'm aware of that specializes in making them:
> traveling at a downward angle and about 600 feet per second as they reached the target zone.
That is incredible. Some BB guns don't even fire horizontally that fast
> Regarding it taking 69 shots to hit the mark, with all the variables that had to be taken into account, “we were thrilled it was so few,” Humphries said.
Just to clarify, I'm pretty sure they're saying that the bullet left the muzzle at 3,300 fps and had decelerated down to 600 fps at time of impact, not that it was moving vertically at 600 feet per second. So the fact that it was moving faster than a BB gun isn't really shocking.
Assuming the bullet is traveling on a purely ballistic trajectory, no weird aerodynamics, calculator is saying it will have a vertical delta V of -235 m/s at 24 seconds. So more like -700 ft/s. But friction is real so I don’t know the real number.
I’m quite surprised they didn’t have the barrel pointed higher. Was the shooter on a plateau?
There shouldn't be any limit to the distance of a rifle shot along a parabolic trajectory if someone builds an appropriate cannon and can shoot many times aye? Artillery shoots much further...
Is there a restriction which prevents a motivated team that can manufacture their own barrels from building a rifle/howitzer hybrid?
Is this an engineering challenge or a marksmanship challenge?
Like... Could you just fire the gun, then put the target where the bullet went an fire again and say its mission accomplished because the real goal is just setting up a gun that stable and precise and deterministic?
>Like... Could you just fire the gun, then put the target where the bullet went an fire again and say its mission accomplished because the real goal is just setting up a gun that stable and precise and deterministic?
No... slight variations in wind and atmospherics across that distance change too rapidly and significantly to make that viable. (Also, you wouldn't need to, you'd just adjust the windage/elevation on the optics and/or fancy rifle mount.)
Also the when the bullet drops from supersonic to subsonic speed, there is a non-deterministic kick that it receives which dramatically reduces accuracy beyond that distance.
Both - the firearm has to be incredibly precise, but you also have to take into account wind and air density to get that much accuracy, and a big portion of marksmanship is accounting for those. Knowing that you'll have a temperature change over a body of water, and how to adjust for that, for example.
Maybe moving the target to the bullet impact would work - walk the shot to the target or the target to the shot? Both still have many other variables - but there is one good reason why they moved the shot instead of the target.
It would be very difficult to find impact points of the misses - The best they could do was listen for where they hit.
* I am more amazed at the quality of the scope that the shooter could place a bullet on a 8" bullseye at a distance of 7.08km. There must be something fascinating to it since, Rayleigh's criterion for resolving two points puts some physical limits to the aperture. To resolve a palm sized mark, you need a sufficiently large aperture on telescope & that's not easy to mount/operate.
* This is one of the neatest images I have seen of the effect of rifling on the bullet, in addition to the thermochemical effect on the bullet tip. The tip at that distance & time of flight goes through sustained heating & there is some evidence of rapid oxidation - much like a piece of metal exposed for few seconds to blowtorch.
That looks like rusted iron residue transferred from the sheet metal backing of the target. They had a board down the middle that they had to cut away to extract the bullet so it was encased in the wood for a while with vaporized metal and water before they got it out.
I am pretty sure in this case the scope is used just like scopes on artillery. You would be interested how artillery scopes resolve from tens of kilometers? They do not.
Rayleigh's criterion doesn't hard limit your ability to aim-- so long as you have a good prior what the image plane projection of the target is.
To give a contrived example. Say we have a function f(x) == a*exp(-(x-m)^2). I evaluate f(x) at 1 and 2 and tell you that the evaluations are f(1)=0.27093242847450331643480903517 and f(2)=1.1666240719274935885932696286. From that, you can tell me the amplitude (a) and peak position (m) with on the order of 100 bits of precision (in this example).
This is contrived because its noiseless and you know the system response perfectly, but I think it demonstrates that an alignment under assumptions need not be limited by rayleigh's criterion.
For this kind of experiment, do you even need a scope?
(Asking as a complete noob).
It seems what you need most of all, is the ability to make the most minute of adjustments to the aim of the rifle, combined with feedback on where the last bullet landed relative to the target.
Then it becomes a bit like Newton-Raphson approximation.
Or are the conditions on the record such that each successive firing must aim from scratch?
One question of interest is how far repeated shots with the exact same rifle aim are going to land from each other. That would depend on changing wind directions and other atmospheric effects. Presumably you pick a day of near zero winds for such attempts.
The design of the bullet itself is interesting. Normally, longer and thinner is more aerodynamic, in any fluid, air or water - it creates less turbulence and drag. But here they found shorter and fatter works better for transonic projectiles:
> The .416 Barrett cartridge is made by “necking down” a .50 Browning Machine Gun (BMG) round to accommodate the roughly .40-caliber bullet. It’s a relatively short, stout bullet that proved ideal for its purpose, Humphries said.
> “Traditionally in extreme long-range shooting, we wanted long, skinny bullets,” he said. “However, we discovered that as a bullet crosses over into subsonic velocity, it flies better if it’s shorter and fatter.”
Bullets in flight have a few dynamical modes where they have a sort of wobble around the direction of travel. They all, when given enough distance, end up tumbling end over end which absolutely ruins accuracy though getting hit with a tumbling bullet is quite destructive for soft targets.
I can totally see trying for a record being helped with a low aspect ratio bullet (er, short and stubby) though this is probably not what you’d actually do if you were doing anything but trying for records.
Fun fact: if you don’t correct for the fact that the earth is spinning which requires knowing your latitude and compass direction, your targeting will be off by an amount measured in feet at this range.
I spent a while developing external ballistics models for a similar use case years ago.
The standard tome of knowledge is McCoy - Modern Exterior Ballistics https://a.co/d/8B6w0qL
> “When a bullet is in flight for that long, you have to take into account the rotational speed of the earth. What you’re shooting at isn’t going to be in the same place it was 24 second ago when you pulled the trigger.”
Wow. Impressive work! I also noted the pitch differential between scope and barrel :O
Impressive, indeed [1], but its the easiest of the corrections they had to do. Its a standard classical physics question and has been included in artillery calculations since at least the late 19th century.
[1] Id imagine that a bullet, being so light compared to a shell, is more affected by fluid flow than the coreolis force. That the correction was needed means they nailed the far more difficult fluid problem.
It's essentially a little bit similar to a mortar shell launch I suppose, at that distance? Reminds me of the fun I had trying to do ultra long distance shots playing Gunbound (South Korean MMMORPG that was similar to Worms) online. Very impressive.
Military snipers in training will practice at a mile+ and take the Coriolis Effect into account (or at least be trained to). Though they'll tell you the likelihood of getting one-shot one-kill is pretty low once you go past a mile of range.
This reminds me about the Ukrainian Snipex Alligator sniper rifle I read about recently. It uses 14.5-millimeter heavy machine gun rounds and it's claimed to be able to penetrate 10mm steel armor at 1,500 meters.
> “The bullet is coming down so slowly, and at about a 48-degree angle, it was just penetrating into the ground without kicking up dust.”
I have no shooting experience, but the arc they have to put into the shot to travel 4.4 miles (~7 km), seems so counter-intuitive to what I associate with shooting. Really impressive work by this team, to have all this calculated out so that they can hit it within 69 shots.
I'm really curious what the success rate of their shot is. From the video, it sounds like the unsuccessful shots were still relatively close by, enough that they seemed confident in being able to still guide it in, so around 1/100 sounds about right, as a crude prior estimate.
104 years ago the https://en.wikipedia.org/wiki/Paris_Gun could shoot 120 km (75 "miles", in medieval units), but it definitely couldn't hit a 200-mm target. Not even in 69 tries. (Yes, it was rifled.)
To me it seems like a more sensible way to hit a target from 7 km away would be to guide the projectile with movable canards, like the VAPP (or, as mentioned elsethread, the M982 Excalibur or XM1156 PGK). You could even do this with a bow and "arrow": once the "arrow" has gained 300 meters of altitude, it has a range of 7 km if its glide ratio is 24, quite achievable (though a regular arrow has a glide ratio of about 0). And you don't have to shoot it straight up, so you can get by with an even lower glide ratio than that.
It seems there is a regular cross-section between technology interests and firearms interest. In most groups of the first type I find there is small group of the second, perhaps owing to the interesting problems to be solved in long range shooting.
Not to detract from the calculations and physical adjustments required to even get close, but a single bullseye at any other range doesn't impress. It's the grouping, three or more on top of each other.
To maybe detract, this was the 69th consecutive attempt. Hmm.
We used to break distance records in video games. The shooter would fire a shot and the spotters moved the target to where the shot landed then the shooter would fire again. Managed to get some amazing distances that way and break the game.
Not trying to downplay this. But with 69 shots, isn't this like Worms computer games where your first shot is guesstimate, and the rest is just nudging the degree "up or down"?
Or they use same approach that NASA uses to launch a rocket to ensure it lands on the moon? I.e some sophisticated calculation (which I assume part of the “some secrets” mentioned in the article).
"“It’s a one-in-a-million shot. They said it’s not statistically repeatable,” he said."
So it's like they're admitting it's almost a fluke, and I appreciate how they're being so upfront about that. They made a follow up video about how it's more like YouTube basketball world records than competition level ones. But still a great achievement.
I would love to see super slow-motion video of the bullet at the end of its flight to see how it’s spinning. It must be significantly slower than when it exits the barrel. Cue slow-mo guys.
Another very interesting thing to see up close and slow-mo would be the transition from supersonic to subsonic, but I have no idea how you’d even begin to get a camera set up to capture that.
I wrote a story where one scene had a rifle shot from just under a mile away. I don't shoot, and did what research I could under the deadline - characters heard the sound of the impact, and then the sound of the actual report shortly afterward. But I wonder if when it's that far away, if the report wouldn't have been audible at all.
[+] [-] SkyMarshal|3 years ago|reply
https://www.thefirearmblog.com/blog/2019/07/30/tacomhq-struc...
https://tacomhq.com/structured-barrels/
The Engineering Behind a TACOMHQ Structured Barrel: https://www.youtube.com/watch?v=C-7LKQYtU48
[+] [-] major505|3 years ago|reply
He done it with every iteration of the AR-15.
The last one was a WWST rifle (a moderized AR with super light materials), and the thing shot like a laser beam.
https://youtu.be/-QoQznLh29Q
[+] [-] exabrial|3 years ago|reply
> traveling at a downward angle and about 600 feet per second as they reached the target zone.
That is incredible. Some BB guns don't even fire horizontally that fast
> Regarding it taking 69 shots to hit the mark, with all the variables that had to be taken into account, “we were thrilled it was so few,” Humphries said.
To give an idea of how difficult this is....
[+] [-] akerl_|3 years ago|reply
[+] [-] hinkley|3 years ago|reply
I’m quite surprised they didn’t have the barrel pointed higher. Was the shooter on a plateau?
[+] [-] Animats|3 years ago|reply
[+] [-] lumost|3 years ago|reply
Is there a restriction which prevents a motivated team that can manufacture their own barrels from building a rifle/howitzer hybrid?
[+] [-] infogulch|3 years ago|reply
[+] [-] bergenty|3 years ago|reply
[+] [-] spywaregorilla|3 years ago|reply
Like... Could you just fire the gun, then put the target where the bullet went an fire again and say its mission accomplished because the real goal is just setting up a gun that stable and precise and deterministic?
[+] [-] Enginerrrd|3 years ago|reply
>Like... Could you just fire the gun, then put the target where the bullet went an fire again and say its mission accomplished because the real goal is just setting up a gun that stable and precise and deterministic?
No... slight variations in wind and atmospherics across that distance change too rapidly and significantly to make that viable. (Also, you wouldn't need to, you'd just adjust the windage/elevation on the optics and/or fancy rifle mount.)
Also the when the bullet drops from supersonic to subsonic speed, there is a non-deterministic kick that it receives which dramatically reduces accuracy beyond that distance.
[+] [-] adrianpike|3 years ago|reply
[+] [-] twothamendment|3 years ago|reply
It would be very difficult to find impact points of the misses - The best they could do was listen for where they hit.
[+] [-] steve918|3 years ago|reply
[+] [-] srvmshr|3 years ago|reply
* I am more amazed at the quality of the scope that the shooter could place a bullet on a 8" bullseye at a distance of 7.08km. There must be something fascinating to it since, Rayleigh's criterion for resolving two points puts some physical limits to the aperture. To resolve a palm sized mark, you need a sufficiently large aperture on telescope & that's not easy to mount/operate.
* This is one of the neatest images I have seen of the effect of rifling on the bullet, in addition to the thermochemical effect on the bullet tip. The tip at that distance & time of flight goes through sustained heating & there is some evidence of rapid oxidation - much like a piece of metal exposed for few seconds to blowtorch.
[+] [-] Vexs|3 years ago|reply
[+] [-] kevin_thibedeau|3 years ago|reply
[+] [-] twawaaay|3 years ago|reply
[+] [-] nullc|3 years ago|reply
To give a contrived example. Say we have a function f(x) == a*exp(-(x-m)^2). I evaluate f(x) at 1 and 2 and tell you that the evaluations are f(1)=0.27093242847450331643480903517 and f(2)=1.1666240719274935885932696286. From that, you can tell me the amplitude (a) and peak position (m) with on the order of 100 bits of precision (in this example).
This is contrived because its noiseless and you know the system response perfectly, but I think it demonstrates that an alignment under assumptions need not be limited by rayleigh's criterion.
[+] [-] tromp|3 years ago|reply
It seems what you need most of all, is the ability to make the most minute of adjustments to the aim of the rifle, combined with feedback on where the last bullet landed relative to the target. Then it becomes a bit like Newton-Raphson approximation. Or are the conditions on the record such that each successive firing must aim from scratch?
One question of interest is how far repeated shots with the exact same rifle aim are going to land from each other. That would depend on changing wind directions and other atmospheric effects. Presumably you pick a day of near zero winds for such attempts.
[+] [-] SkyMarshal|3 years ago|reply
> The .416 Barrett cartridge is made by “necking down” a .50 Browning Machine Gun (BMG) round to accommodate the roughly .40-caliber bullet. It’s a relatively short, stout bullet that proved ideal for its purpose, Humphries said.
> “Traditionally in extreme long-range shooting, we wanted long, skinny bullets,” he said. “However, we discovered that as a bullet crosses over into subsonic velocity, it flies better if it’s shorter and fatter.”
[+] [-] colechristensen|3 years ago|reply
I can totally see trying for a record being helped with a low aspect ratio bullet (er, short and stubby) though this is probably not what you’d actually do if you were doing anything but trying for records.
Fun fact: if you don’t correct for the fact that the earth is spinning which requires knowing your latitude and compass direction, your targeting will be off by an amount measured in feet at this range.
I spent a while developing external ballistics models for a similar use case years ago.
The standard tome of knowledge is McCoy - Modern Exterior Ballistics https://a.co/d/8B6w0qL
[+] [-] themodelplumber|3 years ago|reply
Wow. Impressive work! I also noted the pitch differential between scope and barrel :O
[+] [-] sbaiddn|3 years ago|reply
[1] Id imagine that a bullet, being so light compared to a shell, is more affected by fluid flow than the coreolis force. That the correction was needed means they nailed the far more difficult fluid problem.
[+] [-] rabi_molar|3 years ago|reply
[+] [-] teaearlgraycold|3 years ago|reply
> At this distance you'll also have to take the Coriolis effect into account.
COD did it first
[+] [-] vitaflo|3 years ago|reply
[+] [-] jonah|3 years ago|reply
https://www.popularmechanics.com/military/weapons/a41283557/...
https://snipex.com/alligator
[+] [-] RajT88|3 years ago|reply
Upon clicking, "This Account has been Suspended. Contact your hosting provider for more information."
[+] [-] saeranv|3 years ago|reply
I have no shooting experience, but the arc they have to put into the shot to travel 4.4 miles (~7 km), seems so counter-intuitive to what I associate with shooting. Really impressive work by this team, to have all this calculated out so that they can hit it within 69 shots.
I'm really curious what the success rate of their shot is. From the video, it sounds like the unsuccessful shots were still relatively close by, enough that they seemed confident in being able to still guide it in, so around 1/100 sounds about right, as a crude prior estimate.
[+] [-] kragen|3 years ago|reply
To me it seems like a more sensible way to hit a target from 7 km away would be to guide the projectile with movable canards, like the VAPP (or, as mentioned elsethread, the M982 Excalibur or XM1156 PGK). You could even do this with a bow and "arrow": once the "arrow" has gained 300 meters of altitude, it has a range of 7 km if its glide ratio is 24, quite achievable (though a regular arrow has a glide ratio of about 0). And you don't have to shoot it straight up, so you can get by with an even lower glide ratio than that.
[+] [-] leveraction|3 years ago|reply
[+] [-] unknown|3 years ago|reply
[deleted]
[+] [-] sponaugle|3 years ago|reply
[+] [-] aliqot|3 years ago|reply
[+] [-] bitxbitxbitcoin|3 years ago|reply
[+] [-] ralusek|3 years ago|reply
[+] [-] bjt2n3904|3 years ago|reply
The hardest part is finding a range that lets you shoot past 300 yards, is near your house, and doesn't require a pricey membership!
[+] [-] oliwarner|3 years ago|reply
Not to detract from the calculations and physical adjustments required to even get close, but a single bullseye at any other range doesn't impress. It's the grouping, three or more on top of each other.
To maybe detract, this was the 69th consecutive attempt. Hmm.
[+] [-] Jemm|3 years ago|reply
[+] [-] Gys|3 years ago|reply
Magical even to me. But statistically, if you try often enough?
[+] [-] infotecht|3 years ago|reply
[+] [-] walrus01|3 years ago|reply
Something like a 2km repeatable shot done with 338 lapua and 26" barrel high accuracy rifle is much more real world.
[+] [-] gbrindisi|3 years ago|reply
[+] [-] unknown|3 years ago|reply
[deleted]
[+] [-] below43|3 years ago|reply
[+] [-] wiradikusuma|3 years ago|reply
Or they use same approach that NASA uses to launch a rocket to ensure it lands on the moon? I.e some sophisticated calculation (which I assume part of the “some secrets” mentioned in the article).
[+] [-] Sporktacular|3 years ago|reply
So it's like they're admitting it's almost a fluke, and I appreciate how they're being so upfront about that. They made a follow up video about how it's more like YouTube basketball world records than competition level ones. But still a great achievement.
[+] [-] hamburglar|3 years ago|reply
Another very interesting thing to see up close and slow-mo would be the transition from supersonic to subsonic, but I have no idea how you’d even begin to get a camera set up to capture that.
[+] [-] tunesmith|3 years ago|reply
I wrote a story where one scene had a rifle shot from just under a mile away. I don't shoot, and did what research I could under the deadline - characters heard the sound of the impact, and then the sound of the actual report shortly afterward. But I wonder if when it's that far away, if the report wouldn't have been audible at all.