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  1. damoncali

    Spin Drift

    Why not just calculate the moments of inertia in a more detailed way (truncated cone for boattail, cylinder for bearing surface, ogival solid for nose.)? You only need a few bullet dimensions to do it. I think the folks that care enough about this level of precision wouldn’t mind inputting a few...
  2. damoncali

    Maximum Length of Spin Stabilized Projectile by Beat Kneubuehl

    Interesting. Not sure it's any better than Miller, though. There is a surprisingly (to me, at least) strong correlation between Cm and bullet length for boattail bullets. (And a very poor one for flat based bullets).
  3. damoncali

    March Genesis - 400 MOA in the Turret

    Hold on. Are you saying the distance between reticle subtensions scale with maginfication, while the thickness of the lines stay constant? I'm not optics expert, but how is that possible?
  4. damoncali

    Single shot vs repeater

    Like others say, short range benchrest guys can (and do) argue about the difference in accuracy. At ELR, it doesn't matter. BUT... a single shot is a whole lot easier to deal with in my view. With a single shot: -You are no longer constrained by what will feed through the magazines - you can...
  5. damoncali

    Spin Drift

    I heard if you put one foot on the ground, spin drift drops in half. But yeah, that's mostly Coriolis.
  6. damoncali

    Spin Drift

    The Spin Drift Argument, Simplified Edition: Q: Is it real? A: Yes. Q: Does it matter? A: Define "matter". Q: How do you calculate it? A: It's complicated. Q: Did you know there is actually a thing called spindrift soda? A: Yes, and that's hilarious.
  7. damoncali

    Spin Drift

    If you’re shooting high power (or anything else that allows for sighters) you don’t need to worry about it. It’s going to be almost identical from shot to shot. It only matters when trying to make first round hits without a sighter, and even then most of us aren’t good enough to call the wind...
  8. damoncali

    Hyper Stabilized Bullets - Jim Boatright

    I can't answer your question, but there's a fascinating paper on M4 accuracy out there that determined that the standard M16 flash suppressor actually improves accuracy very slightly. This surprised me since it's asymmetrical and that can induce yaw, but it turns out that cancels out some other...
  9. damoncali

    4DOF Bullet Library

    In my view, no. RADAR Drag curves are the primary benefit of the Hornady calculator, in spite of the marketing that sort of spins the MPM aspect (nothing wrong with MPM, but accurate drag data is much more important). FYI - Lapua uses custom curves too if you'd prefer their bullets.
  10. damoncali

    Advanced Marksmanship AMMO how much ?

    Depends on what I’m shooting. I can shoot f class all day. It’s pretty easy and an 18 pound rifle doesn’t kick much. Shooting off hand service rifle? I’m mentally beat after 40 rounds. Anything more than that is counterproductive for me. Steel buttplate .45-70 500gr loads? 5 is plenty, thanks.
  11. damoncali

    Hyper Stabilized Bullets - Jim Boatright

    It just so happens that I read and implemented a version of McDrag last month, and I had some of the same concerns, although to be honest, I never looked into it in detail. I did note that at least some of his sources appear at first glance to be on top of the problem, but I was left wondering...
  12. damoncali

    Hyper Stabilized Bullets - Jim Boatright

    Jim, I was rereading your paper, and I'm curious about this bit: "I suspect that in developing his similarity-based McDRAG program for projectiles usingogive head-shapes, McCoy was inadvertently predicting the total coefficients of drag CD’sfor projectiles flying with significant, but...
  13. damoncali

    Hyper Stabilized Bullets - Jim Boatright

    I don't know of the reasoning behind the drilled base - I assumed the intention there was to play around with the weight distribution rather than something to do with base drag? But yes, I'm differentiating only between yaw drag and axial drag, both of which have multiple sources. Cd = CD0 +...
  14. damoncali

    Hyper Stabilized Bullets - Jim Boatright

    The dumb version is that BC is composed of two contributors to drag. The first - CD0 - is the drag the bullet experiences along its axis - when yaw is zero. The second is CDa, which is "yaw" drag. It's the drag attributable to the bullet's yaw relative to the oncoming air flow. If a bullet is...
  15. damoncali

    Hyper Stabilized Bullets - Jim Boatright

    It's not the barrels, it's the bullets you need to worry about. If you've ever seen someone shoot 90 grain .224 bullets, one of the challenges is to keep them stable without blowing up the bullets. Solids mitigate this problem because it's the jackets that fail. The other issue with really fast...
  16. damoncali

    Range Report Melting Polymer Tips?

    In a former life, I was an aerospace engineer, and we used a polysulfone very similar to what's in their patent to make specialized electronics boxes. It's a pretty amazing material. It's just regular plastic, but we were able to use it in an application that 99% of the time requires aluminum...
  17. damoncali

    Range Report Melting Polymer Tips?

    I was responding to the question about what Hornady did to the polymer chemistry to make it more heat resistant. The answer is they used a different plastic. Its not a process, just a different material.
  18. damoncali

    Range Report Melting Polymer Tips?

    You can find the details in their patent application. They're just using different kinds of plastics - there's no special sauce or magic going on. Details here: https://patents.justia.com/patent/20160169645
  19. damoncali

    Advanced Marksmanship Determining Altimeter Setting? Density Altitude Calculation

    Poor man's kestrel: https://www.amazon.com/Sun-Company-Altimeter-203-Weather-Trend/dp/B0012A8UYK/ref=lp_219368011_1_2?s=sports-and-fitness&ie=UTF8&qid=1517888508&sr=1-2 Just put that number in for station pressure and you're good to go (I'm assuming you've got a grip on temperature).
  20. damoncali

    Best device for ballistics app

    You guys are buying windows phones just to run cold bore? Must be some good stuff. Yikes.
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