Re: bullets fragmenting??
I own two 22-250 Ackleys.
First, the usually overlooked question is; what purpose is this rifle to be used?
Most are used as predator guns. That is my purpose.
Second question, day hunting, night hunting, long range or maybe a wide range of applications?
I will give you my opinion right now, unless you are interested in very long range, an 8 twist is not correct. The reason is that, you will see much shorter barrel life and the VLD bullets do not kill well at extended ranges. You get runners, and that is never good. Ground squirrels, maybe, but coyotes deserve a better fate.
One of my barrels is a Shilen 1X12" and the other is a Hart 1 in 14". At the speeds you will see, there is no reason to spin a 60 bullet, in an 8 twist at that RPM when all you really need is about 180,000 for acceptable accuracy. The muzzle velocity is all I need to shoot 65 grain bullets very accurately. 70 grain VLD, not so much. I never tried 70 grain Bergers in the 12 twist because of the above concern about actually killing (bang/flop) a coyote rather than seeing him spin and run off, never to be found without dogs and a waste of good hunting time.
Therefore, if you intend to hunt with this rifle, Do yourself a favor. I suggest that you change your order to a 12 twist.
Lastly, yes, there is a possibility of vaporizing bullets at extreme RPM. I have done so with 55 grain Bergers. They were grouping very nicely at 100 yards and blowing up before 200, which I found out by shooting at a cooperating coyote out at about 200, or so. He just looked at me and I thought I must have bumped the gun? Checking it out, those bullets that were grouping so well at 100 never printed on paper, at 200.
Maybe not always, but certain bullets will not handle that RPM, and that's what it is, not speed, per se, it is the centrifugal force that causes some bullets to fly apart. Ergo, avoid a fast twist unless absolutely necessary to stabilize a really long bullet. You said you are hunting coyotes. Don't use these type of bullets. Free advice, and worth the price. BB