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So John Connally was hit in his back to the right of the shoulder, had his fifth rib shattered, and had the missile exit below his right nipple, right? Considering the temporary cavitation of a low-velocity tumbling bullet, how did that not cause serious damage to his liver, which would have been within an inch or so near the fifth rib/exit point? There was never mention of serious damage to Connally's liver.
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A high-velocity bullet just going near your liver can cause serious damage to it. And all of these articles and books say that a tumbling high-velocity bullet can make an even bigger temporary cavity. Meanwhile, a low-velocity (subsonic) bullet may give a better explanation for why Connally wasn't killed.
Still no answer for why your pin-the-headwound on the drawing riff has any actual significance in the context of the known evidence?
Your latest flight of fantasy has a couple of serious flaws.
1. Low velocity projectiles of any diameter rarely "tumble" inside a soft target - they may "yaw" in soft tissue - but other than changing direction after impacting the skeletal structure they do not tumble.
About the terms of art you're using.
As defined by the U.S. military, to be considered as a "High-Velocity" small arms projectile, the muzzle velocity needs to be at or above 3,500 feet per second.
The Carcano 6.5 x 52R starts out at approximately 2,000 FPS out of the Carcano barrel, m/l 2,200 FPS out of the longer standard issue rifle barrel.
The Carcano round doesn't make the cut as a HV round.
To the question of the projectile "tumbling."
One of the earliest myths concerning the lethality of the original M193 5.56 mm round and the M16 was that the bullet "tumbled"
before impact.
It was an explanation that untrained individuals bought into at face value.
The fact was/is that the very earliest examples of the AR-15 as adopted was that the rifling twist was 1 turn in 14 inches in a 20 inch barrel. That was just enough to stabilize the 55 grain issue round, but once the projectile hit anything but air the bullet would destabilize. The theory being that the destabilized projectile would cause greater injury to a soft target. The reality was that the round fired from a 1/14 barrel wasn't accurate enough to be useful and because the projectile destabilized so easily, a soft target behind almost any type of cover was relatively safe. The problem was corrected by increasing the rate of twist to 1/12, but the myth lingered on amongst people who didn't know any better. A projectile "tumbling" as a part of the exterior ballistics of the projectile is a classified as a deficiency if it's the result of the weapons' design.
Projectiles that "tumble"
after penetration (the correct term is "yaw.") don't behave in the manner that layman believe. As the projectile destabilizes, it begins to rotate along it's axis and some types of projectiles (steel core 7.62 x 39 combloc comes to mind) will swap ends as it travels through a soft target and will also lose velocity. Such a projectile doesn't act like a circular saw inside a soft target.
2. The projectile that wounded Connally was barely supersonic at impact. Your speculation of cavitation isn't based on the facts.