Sorry guys. I meant to come back to this sooner, but I have been loading ammo like a madman for my new standard 6br I just got back Wednesday.
Thanks for all your posts. Unfortunately, there are conflicting opinions on this subject so I have not told the fellows in the debate about this site as of yet. We need to come to an agreement on the subject before I start the argument again with these guys.
The reason I brought this whole thing up was because I was shooting a match Wednesday at 100 yards for group with my fast twist 6br improved which is really better suited for 1000 yard shooting. I made the mistake of mentioning that the 105 amax that I was shooting needs more distance to settle down and shoot it's best and the guys there (who are not long range shooters, just 100 yard br shooters) just about laughed me off the range! Of course, Old Bear had just left so I was all alone trying to tell these guys about the world that exists past the 100 yard target frames. Then to make matters worse, one guy mentioned how he just built a 220 swift on an 8 twist barrel and was shooting 60 grain bullets in the thing. I told him that the rpm's involved in that scenario may not let that bullet shoot well, and told him to try a 75 grain Amax or 80 grain Sierra MK and they will handle the rpms better because they will be have a slower velocity, thus reducing the rpm's. Then we kinda got confused on our terminology, and one thing led to another and the debate of whether the 60 grain or the 80 grain bullet has more revs per distance. I told him that they both have the SAME rpd's. Each bullet revolves 1 time in 8 inches regardless of speed.
Then it got into an argument of if each bullet is still revolving 1 time in 8" clear out to the end of it's traj.
Now, there are differing views on this as mentioned in earlier posts by you fine gentlemen. And in fact, I did tons of research on this until about 3:00 AM and actually found differing scientific info! This is not good. [img]/ubbthreads/images/graemlins/frown.gif[/img]
It seems that there are several reputable sites that give conflicting info on this subject. I believe that it is all theory and no one has actually devised a way to "capture" a bullet at long range on slow mo video to see if it is still spinning the same rpd's as it was when it left the muzzle!
I found this:
Scroll down to where it says, "some caveats"
What I believe happens is that if there are no marrs in the jacket, and no voids in the core, that 80 grain bullet and the 60 grain bullet are still spinning just fractions under 1 time in 8" at 1k. I believe that if it weren't true, the bullet engineers would rate the needed twist to spin the vld's in an additional boundary. For example, they would list it on the box that it needs an 8 twist in the barrel out to say 600 yards. Then from there out to 1k it needs a 7 twist. Then it needs a 4 twist for 1500 yards and so on. Since that 80 grainer can and does get shot in all ranges without deviating from the 1-8" twist, I would tend to think that it is still spinning at the same rpd clear out until it hits the ground and as long as the rpm's are held above the loss of stability point, it should continue to do so. Of course, at one point, the velocity will dip below the speed of sound and consequently the rpms may not be sufficient to keep those long bullets stabilized.
Anyhow, I have researched until I can't research no more. And still, I find conflicting answers to the questions.
Oh well, I have loading to do anyways!
Catch you guys later. GG