Re: Min amout of knockdown force at 700yrds?
I'm not a big one to try and put numbers to something like that. I think it's an attempt to use mathematics on something that is really tough to quantify.
I've seen no difference in killing power on deer with any of several different cartridges. For instance the little .243 Win & 6mm Rem have caused instant death, same as far more powerful rifles... Instant death is pretty hard to trump. It doesn't get more instant when more power is applied.
Put a good quality expanding bullet into the heart and lungs, with enough velocity to initiate expansion, and you've got venison. They're pretty easy to kill. Very difficult to sustain life when the lungs are shredded and the heart perforated.
Then again, I haven't shot one at 700 yards yet.
I've read a lot of different theories about killing power, expressed in foot-lbs of energy for various size animals at various ranges... After seeing quite a few deer killed over the years, I'm not so sure the numerical theories make a lot of sense for determining "knockdown" or "killing" power. I'm also not sure "knockdown force" is a really good term. In simple physics, if your rifle generates enough force to knock down a deer, it's also going to knock you down when you shoot it... At least that's the way I remember my High School physics from about a million years ago!