Re: Energy needed ?
I read an article quite awhile ago in a newstand magazine of a guy who was a metal fabricator and wanted to know the same thing. He had what I believe was called an English jack pounder in his shop which is basically a huge crushing anvil machine that hits very fast repeatedly. Some of the custom chopper builders use these machines to custom make gas tanks. They pinch sheet metal between the anvil and the crusher and can alter the crushing pressure by a switch.
Anyhow, this guy decided to put an elk's shoulder blade in this machine to see at what pressure point it would break. He started at a low setting and worked his way up until the blade broke and it was just a tad over 800 Ft/Lbs. This shoulder blade was a rather large one and came from a Colorado 6x6 bull.
This article hit home with me because I had already deduced from my own experiences with killing elk and witnessing elk being killed that it was somewhere between 750 to 1000 ft/lbs when I ran the ballistic chart on the particular load for the range in which the elk was hit.
On a side note, the needed energy to break the spine is much lower. I have spinal tapped a spike elk at 830 yards with the same load (except it was a Scirocco bullet) as the load that killed my 820 yard cow, and it removed a 4" section of the spine from the elk into a branch of a quaking aspen tree 6' behind the elk! I wish I had pictures of that, but that was on a hunt where I was alone and I didn't want the extra weight of the camera and I didn't think that anyone would want to see a picture of just a dead spike anyway. I have since learned that you ALWAYS take a camera no matter how cumbersome it might be.
A friend of mine used his camera last fall on a hunt not to take pics of his trophy, but to take a pic of some lowlife poaching a moose during the deer hunt! He got a free hunt out of it courtesy of the Utah division of wildlife remorses-err a I mean resources.
If it's not far, it's boring.