Definition of "knock-down"
I would have to say "the perfect combination of bullet and powder to knock an animal off it's feet". This would mean no exit wound with the animal absorbing 100% of the energy from the projectile. Shot placement is also a factor here. Do you go for the vitals, or hit it in the shoulder to keep it from running? Obviously if you hit it in the shoulder, you would up the odds of no exit wound. Much more mass and bone to penetrate in this area. Same shot placed in the vitals would most likely pass through the body.
I've witnessed deer running 300yds. with a perfect vitals shot (form a 50cal.) hitting both lungs and heart. Incredible!
I can only refer to an episode of "Myth Busters". The test was, they took a pig carcass hung it from a chain, and had a link of the chain perfectly balanced on the point of a hook. They fired countless different rounds at it starting with a .22 rim-fire. In the end, the only round that got the carcass moving enough to knock it off the point of the hook was a 12ga. slug with no exit wound!
Your thoughts gentleman?
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