lloyd smale - I like your response. It got me to thinking. The 140 Nosler BT was probably only part of the cause of the results I got at long range with my 7 MM STW. The other part, maybe a larger part is the twist rate of my gun, 1-in-11. I should have thought about this earlier since I have a lot of experience on twist rates in 7 MMís. First, Nosler shows load data for most 7 MM cartridges using test barrels with a 1-in-9 twist. Using the equation for centrifugal force one can calculate that a 1-in-9 twist compared to a 1-in-11 twist for a bullet at the same velocity would generate almost 50 percent more centrifugal force in the bullet. If one has read about bullets blowing up in the air on the way to the target, they would probably agree that twist rate would have an effect on bullet expansion. Also, I have read that the spin of a bullet slows does not slow down as quickly as its velocity as it goes down range.
I bought a 7 MM Weatherby magnum when in high school over 50 years ago and had it re-barreled three times since then. The factory barrel was had a 1-in-12 twist and I shot quite a few coyotes with it. It generally produced exit holes of 1-1/2 inches on coyotes. A classmate told me how his fatherís .30-06 made 3 to 4-inch exit holes on coyotes. I thought that was a bunch of bull since my 7 MM was a much higher velocity rifle. Then just after college when the factory barrel went bad, I had it re-barreled with a barrel with a 1-in-10 twist. The first coyote I shot with it had a 4-inch exit hole and this was with a 139-grain Hornaday bullet which was supposed to be a game bullet, not a varmint bullet. Subsequent coyotes with that barrel also had large exit holes.
Then when that barrel eroded, I had it re-placed with a barrel with a 1-in-9 twist and later had it re-barreled with a barrel with a 1-in-12 twist chambered for 7 MM STW. I wanted a rifle which would shoot as flat as possible for 400 yards. It shot 120-grain Hornaday hollow point varmint bullets at 3,650 fps. Again, it produced smaller exit holes on coyotes. In addition, I shot 17 antelope with it and mostly from 300 to 400 yards and that bullet went completely through the antelope every time generally making an exit hole of about 1-1/2 inches. Anyway, I am thinking that bullet manufactures use a standard twist rifle when designing and testing bullets and in my 7 MM rifle with slower twists their bullets donít behave like they were designed to behave.
The old 7 MM rifle was given to my son after my current 7 MM STW was put together with the 1-in-11 twist barrel. I had this rifle put together because the old rifle would not shoot Ballistic Tips accurately and it appeared, they were much superior to the old 120-grain Hornaday hollow points which shot well in the old gun. The new gun would not shoot the 120-gr BTís like I had hoped but it does shoot the 140-gr BTís well. I never noticed large exit holes on quite a few coyotes shot with it nor on the 500-yard antelope I got with it that ran 100 yards after a good hit through the lungs. Neither did the two deer I got with it at around 500 yards have large exit holes and the deer I got at almost 600 yards only had a very small exit hole.
My conclusion is that if the fragile 140-grain Berger VLD hunting bullets will not shoot accurately in it (for shooting to 600 yards or more), I will have to have it re-barreled with a faster twist barrel. Heavy long range bullets are not be stable from the current slow-twist barrel at low temperatures and most lighter bullets (except the Berger) will probably not expand well at long range with it because of the slow twist.