You missed the part about the ice needle containing the tetrodotoxin. A tiny, tiny dose leads to sure death from an "apparent heart attack." It is not the projectile; it is the poison. You need to read carefully about how this works.
No, muzzle velocity is limited by what can be achieved by the expansion of a gas under pressure and is related to the speed of sound of the gas. This is not a weapon powered by combustion, which makes higher velocities possible (higher gas temperatures). Lewis and Clark had a smoothbore long arm that was powered by compressed air, with which they hunted for (e.g.) deer during their expedition to the Pacific coast. I saw an example of such a gun at the reconstructed Fort Clatsop. No problem getting enough energy to do the job.
The sabot separates from the projectile within a yard of the muzzle. The assassin picks it up and exits Stage Left. This is not theory. Sabots have been around for a long time. They could even be made of environmentally degradable material.
No shock waves. I worked interior ballistics of rocket motors; I know what a shock wave is, and they do not occur for air pistols/rifles. You open a valve, pressure mounts, expands down the barrel, and it is over with. No detonation. No shock. Rapid acceleration onset, but not a shock. Even a conventional gun has a combustion process, not a detonation process. Any such harmonic response by the barrel would be less than for a regular firearm, since things are not happening as fast.
"Second-order factors" at subsonic speed? I am an aerodynamicist by training, and you are talking through your hat. Air density is the only issue, and so long as it doesn't change dramatically over the path of the projectile, there is no problem. And even if it did change, there would not be much effect. Now you are grabbing at straws, since air density would affect ANY projectile weapon. A crosswind would be more of a problem.
As for the scope, I have to chuckle. Somehow a man with a pistol will be ignored---but a man with a pistol AND A SCOPE will stand out like a sore thumb? Do you realize how ridiculous this is? If he is going to be ignored for a pistol, the scope will not make him more obvious. This is part of the stealth of an assassination.
A shock wave is a discontinuous change in pressure and density, obtained only through hard impact or from a detonation. (A step function, not a Dirac delta, which is not a physical process.) Neither are present in regular firearms or airguns. There may be a response to pressure loads, but they are not "shock." And common experience shows that they are no hindrance to high accuracy of such mediocre projectiles as spheres (BBs). I've had occasion to instrument a solid propellant rocket motor to track down an actual shock wave transient in its ignition process. We needed to have a transponder that had a time resolution of about 1 millisecond (1000 Hz). This is nothing like that. The practical reality (as I mentioned) is that there is no such problem with airguns.
You are making it up as you go along. First, the scope will be noticed, but not the pistol. Now, the scope will be noticed so much that the pistol will also be noticed? Why don't we agree that a competent assassin will take pains to conceal what he is doing? There is no question that the scope will help him hit his target point. (I am a shooter and hitting anything within a hand at 50 feet is not easy with iron sights.)
I happen to be a retired aeronautical engineer, who knows a lot about shock waves in tubes (graduate research and production engineering). I also have a long background in firearms information. You happen to be a guy with a little bit of knowledge, who is reaching wrong conclusions.
Then you would know it would be pointless to try to impart rotation to a needle. Any perturbation and the needle would twist and rotate like a propeller (preferred rotation axis aligned with maximum moment of inertia). And you would also know that there is nothing wrong with aerodynamically stabilized projectiles (like arrows) which are capable of considerable accuracy. And you would know that a sabot could be made of (e.g.) fibrous materials that would self-shred upon expulsion from the muzzle, after separation from the needle (or call it a flechette). You would know all these things and would not argue against them. You would know that if the assassin were to use a pistol, or a silenced pistol, it would be the same operational scenario requiring concealment. You would know that a modest sight magnification would greatly assist any targeting at distances of 50 feet or so. You would know all these things.
But do you? You certainly do not know what a shock wave is. Or that there are no such phenomena even internally to a firearm. Or that the velocity attainable from a gun system is proportional to the speed of sound in the propellant gas (which is why hot hydrogen gas guns are used to project high-altitude sounding projectiles).
I apologize for any insult to your professional standing, but you must realize that you should have known these things.
You missed the part about the ice needle containing the tetrodotoxin. A tiny, tiny dose leads to sure death from an "apparent heart attack." It is not the projectile; it is the poison. You need to read carefully about how this works.
No, muzzle velocity is limited by what can be achieved by the expansion of a gas under pressure and is related to the speed of sound of the gas. This is not a weapon powered by combustion, which makes higher velocities possible (higher gas temperatures). Lewis and Clark had a smoothbore long arm that was powered by compressed air, with which they hunted for (e.g.) deer during their expedition to the Pacific coast. I saw an example of such a gun at the reconstructed Fort Clatsop. No problem getting enough energy to do the job.
The sabot separates from the projectile within a yard of the muzzle. The assassin picks it up and exits Stage Left. This is not theory. Sabots have been around for a long time. They could even be made of environmentally degradable material.
No shock waves. I worked interior ballistics of rocket motors; I know what a shock wave is, and they do not occur for air pistols/rifles. You open a valve, pressure mounts, expands down the barrel, and it is over with. No detonation. No shock. Rapid acceleration onset, but not a shock. Even a conventional gun has a combustion process, not a detonation process. Any such harmonic response by the barrel would be less than for a regular firearm, since things are not happening as fast.
"Second-order factors" at subsonic speed? I am an aerodynamicist by training, and you are talking through your hat. Air density is the only issue, and so long as it doesn't change dramatically over the path of the projectile, there is no problem. And even if it did change, there would not be much effect. Now you are grabbing at straws, since air density would affect ANY projectile weapon. A crosswind would be more of a problem.
As for the scope, I have to chuckle. Somehow a man with a pistol will be ignored---but a man with a pistol AND A SCOPE will stand out like a sore thumb? Do you realize how ridiculous this is? If he is going to be ignored for a pistol, the scope will not make him more obvious. This is part of the stealth of an assassination.
A shock wave is a discontinuous change in pressure and density, obtained only through hard impact or from a detonation. (A step function, not a Dirac delta, which is not a physical process.) Neither are present in regular firearms or airguns. There may be a response to pressure loads, but they are not "shock." And common experience shows that they are no hindrance to high accuracy of such mediocre projectiles as spheres (BBs). I've had occasion to instrument a solid propellant rocket motor to track down an actual shock wave transient in its ignition process. We needed to have a transponder that had a time resolution of about 1 millisecond (1000 Hz). This is nothing like that. The practical reality (as I mentioned) is that there is no such problem with airguns.
You are making it up as you go along. First, the scope will be noticed, but not the pistol. Now, the scope will be noticed so much that the pistol will also be noticed? Why don't we agree that a competent assassin will take pains to conceal what he is doing? There is no question that the scope will help him hit his target point. (I am a shooter and hitting anything within a hand at 50 feet is not easy with iron sights.)
I happen to be a retired aeronautical engineer, who knows a lot about shock waves in tubes (graduate research and production engineering). I also have a long background in firearms information. You happen to be a guy with a little bit of knowledge, who is reaching wrong conclusions.
Then you would know it would be pointless to try to impart rotation to a needle. Any perturbation and the needle would twist and rotate like a propeller (preferred rotation axis aligned with maximum moment of inertia). And you would also know that there is nothing wrong with aerodynamically stabilized projectiles (like arrows) which are capable of considerable accuracy. And you would know that a sabot could be made of (e.g.) fibrous materials that would self-shred upon expulsion from the muzzle, after separation from the needle (or call it a flechette). You would know all these things and would not argue against them. You would know that if the assassin were to use a pistol, or a silenced pistol, it would be the same operational scenario requiring concealment. You would know that a modest sight magnification would greatly assist any targeting at distances of 50 feet or so. You would know all these things.
But do you? You certainly do not know what a shock wave is. Or that there are no such phenomena even internally to a firearm. Or that the velocity attainable from a gun system is proportional to the speed of sound in the propellant gas (which is why hot hydrogen gas guns are used to project high-altitude sounding projectiles).
I apologize for any insult to your professional standing, but you must realize that you should have known these things.