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A "stability" problem that shows up at 1500 yards is a dynamic stability problem. Gyroscopic stability problems will show up inside of 50 yards. If the bullet does not outright tumble, then it will demonstrate increased drag and large shot to shot variations in drag if there is a gyroscopic...

You are confusing the ideas of gyroscopic stability and dynamic stability. The gyroscopic stability is the smallest when the bullet leaves the muzzle. However, depending on the bullet design, a bullet can have excellent gyroscopic stability at the muzzle and then develop dynamic instability...

We are always eager to consider hard data that suggests our stability formulas may not be as accurate as our data suggests (5%). I'm sorry if reference to a published paper describing the details struck a bad chord with you. I had already provided the main reason why the original Miller...

http://arxiv.org/ftp/arxiv/papers/1401/1401.4187.pdf The published paper is a good place to start.

Open tipped match bullets often have higher stability than indicated by the most widely used stability formula. This formula assumes a bullet of constant density, and the open space at the front does not meet this assumption. We have developed and tested modifications of the original Miller...

The above answer was very good, but left room to get more quantitative. The dependence of stability on velocity goes as the 1/3 power of velocity. This means a 10% increase in muzzle velocity only gives you a 3.2% increase in stability. The dependence of stability on barrel twist rate goes as...

It may be an error to assume that muzzle velocity remains constant over big changes in air density. We've seen 140 fps more at 7000 ft (Colorado) than at sea level (Louisiana) for the same loads. We reckon its the weight of the extra air in the barrel at sea level. Something to consider if...

http://www.bergerbullets.com/twist-rate-calculator/ Your stability calculator suggests bullets may have a reduced BC for SG < 1.5, but that the BC is constant for SG >= 1.5. Is there data in your book contradicting your stability calculator? I was under the impression that your stability...

You seem to be challenging the validity of the Miller stability formulas (which we have experimentally verified) as well as the long established results from Sierra that BC is independent of stability for well-stabilized bullets. This is a more interesting technical discussion than the other...

We've validated the stability formulas by turning down the stability at low Mach numbers. The bullets tumble when the appropriate formula predicts SG < 1.0 and do not tumble for formula predictions that SG > 1.0. It's not just the formulas suggesting stability, the experiments confirm it. I...

I did not mean to imply that my "way is better" only that determining drag coefficients over the whole range of Mach numbers is more meaningful than extrapolating the curve from a small number of points. Isn't this the point of having "custom drag curves" that some in ballistics are now...

Thank you for clarifying the issues from your book that I had asked about earlier. The stability was over 1.5 for all the data points in the attached figure. Sierra has done some very convincing work showing the consistency of BCs (and drag coefficients) for different twist rates, as long as...

A scientific/engineering discussion should focus on the facts rather than the personalities. The above questions were posed to the author of published material because they concern details that only the author (or others with inside information) would know. Those not privy to the original...

Typo, should have been "almost 20 years ago." Sorry about that.

The dope was checked by shooting at long range, and I did notice the need to adjust the elevation more than expected. I simply made a chart of the measured elevations actually needed at the ranges at which shots were expected. Perhaps there was a lack of due diligence on my part, but at that...

Our first hint that there might be a BC problem with the Bergers was when the 115 VLD failed to expand on a long range deer. At the time, the advertised BC was 0.523. We started measuring BCs shortly after this because we wanted to know the impact velocity more accurately to understand...

Thanks for your comments and your insights. Given the number of inquiries we had about aluminum tipped bullets and the fact that we were distributing the spreadsheet privately, we decided to make it public so as not to give any (real or imagined) advantage to those to whom we had sent it...

Thanks for your ideas and insights. We're aware of the bullets with the Corbin dies, but a number of parties have taken to adding the Corbin aluminum tips to various commercial bullets by trimming the tips and prepping the tips to accept the aluminum tips. Not everyone who has contacted us...

Most know that Don Miller published an accurate formula for computing gyroscopic stability of constant (or near constant) density bullets in 2005. This formula has been incorporated in several ballistics calculators including JBM, ColdBore, etc. Don knew that his formula would be overly...

Depends on your altitude. We've stabilized the SS109 bullet from a 1 in 12" twist at 5000 feet. At sea level, you will need a faster twist, but how much faster depends on velocity. The SS109 is an odd bullet. It is much harder to push through the barrel, so at the same pressure, it will...