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.