I would agree velocity help's kill fast. 100gr Hornady Spire point bullet's from my 25-06 killed deer like a lighting bolt. But there was also a huge amount of internal damage. That bullet was going a bit over 3300FPS, haven't shot it in a lot of years. Moved up to the 117gr Hornady and the instant kill went way for the most part. What would happen is the deer would be hit, walk off maybe 20' and lay down dead. Used that bullet and load for a long time. Chronographed it at 3079FPS. Internal damage was greatly reduced with the 117gr bullet. Of course central nervous system hit's gave the same results with either bullet. I've never shot an animal through any bone's to speak of, heavy bones that is and I suspect the 100gr bullet would have a tuff time due to a light bullet and high velocity.
Seem's I read where the old 6.5x55 had a 7.5" twist in it. Needed it as it was used with heavier bullet's than we generally use today, 150+ gr. My 6.5x06 is a 1-9". Hornady told me the 1-9 wouldn't stabilize their 140gr bullet, did very well in my rifle. They alo told me it wouldn't stabilize their 123gr match bullet, I'll never know. Come's to match bullet's, I love Sierra Match King's. Probably other match bullet's may well be as good but I have always had great result's with MK's. Now Sierra told me my 1-9 would stablize their 140gr MK but wouldn't their 142gr MK. Don't understand that at all!
Had a 6.5x55 put together for the ex years ago on a Parker Hale 1200. Shooting across a chronograph it just did not lag far behind the 6.5x06. I've never seen or shot the 260 Rem or the 6.5 Creedmoor but I suspect neither of them would be all that far behind either but I doubt as close as the 6.5x55. Case is simply bigger though not quite as big as the 30-06 case. I have tried the 129gr Hornady spire point and 140gr spire point's in my 6.5x55 and can't decide which I like best. A flaw for me with velocity is if a bullet is not well enough constructed, to much can tear up the bullet. Got to a heavier bullet and depending on the bullet, you could well need a faster twist to stabilize the bullet. As for RPM's, I haven't got a clue what that might be in any bullet or cartridge and I would not rely on it to do much. I think it's simply a side product of velocity and twist. As for a high speed drill, I suspect the secret to that is a drill bit that can with stand the heat high speed will give it. The faster drill will develop higher heat and it can withstand that heat I'd think. Something about velocity. I used to use a lot of the old Hornady 50gr SX bullet's in a 222 Rem. Hornady cautioned that at 3500fps the bullet's would come apart in the air. We tried that with a buddy's 22-250, they did come apart right at 3500FPS. I suspect with them the problem was the velocity was getting the bullet to hot and the jacket wasn't thick enough to hold it together.
Two thing's I think are clear about bullet's, if not heavy enough, velocity can tear them up, usually impacting if velocity is to high. And I think a proper bullet for cartridge can withstand more than we think. We keep thinking we need thing's like partitions, bonded core and monolithic bullet's. They seem to serve only one purpose to me, they allow you to used lighter bullet's at higher velocity's without poor bullet performance, they hold together! Years ago I shot some difference bullet's into bundled newspaper at 100yds to see what the bullet's would do. Two really stood out, 154rg Hornady and 180ge Speer hot core from a 7mm mag. Both bullet's retained 85% of their weight, cup and core bullet's. The core of the Hornady was loose inside the jacket, could twist it around with my finger's. The Speer Hot Core stayed tight in the jacket. Now that 85%, compare that to what Nsler partition and interbond are designed to do. By design they maintain 70% of their weight. That's what Nosler told me. Weather it's good or bad, I'm not sure. I think it's a fact that those Nosler bullet's do very well. In the end though for a bullet to do it's job, it must maintain enough weight to penetrate to the vitals and a bit more to destroy then and it must be placed to make use of the way the bullet is made. I can guarantee you that a 22 LR can kill a deer every bit as fast as a 270 Win. But you have to use it within it's limits and anything less and it wounds, nothing more. Used withing it's limits, velocity has little to do with it, you get close nd you place the bullet very precisely! I read an article some time back about the world record Grizzly bear, it's number two today. It was killed by a woman coming in off a trap line with, get this, a 22 long RF in a single shot rifle! Velocity had to play a role but bullet placement played a much bigger role and her understanding of how to use what she had.
