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  1. J

    2 "Train of thoughts" arising in ELR

    I am frankly mystified as to how the area inside a hollow base can exceed the area surrounding it on the outer surfaces of the bullet. Minie ball projectiles do not work quite as Capt. Minie, and most others, envisioned they would. The original design required a separate, flat-based "expander"...
  2. J

    2 "Train of thoughts" arising in ELR

    Yeah, "pressures" are isotropic and create no shear stresses, OK, got it. I said we would be using quick-static loading analyses in the paper because we were primarily looking at radial and tangential effects (per Roark's 7th Ed, p 36). I am just a pedestrian physicist, not really a mechanical...
  3. J

    2 "Train of thoughts" arising in ELR

    I found it easier to specify a circular arc headshape for the machinist than one of the more complicated headshapes (like Sears-Haack LD) for very little drag reduction at any given nose length. I tried to keep the OAL of the projectile as short as possible for practical reasons. If these...
  4. J

    2 "Train of thoughts" arising in ELR

    Pressure would be normal to all surfaces if they were hydrostatic. Rifle bullets leave the case neck with a mass of unburnt propellant stuck onto the afterbody. Early pressure rise compresses the propellant into something like a solid rocket fuel. The propellant mass fractures conically as the...
  5. J

    2 "Train of thoughts" arising in ELR

    I decided to optimize my new copper ULD bullet design for maximum supersonic range instead of worrying about their behavior in the transonic and subsonic flight regimes. I wanted to carry maximum useful kinetic energy to the greatest possible distances. I use a 7.5-degree boat-tail which is 0.7...
  6. J

    2 "Train of thoughts" arising in ELR

    I just read this interesting discussion thread and thought I might throw in my 2 cents worth. I have always been firmly in the light, high-speed bullet camp for long-range riflery provided the BC of that bullet is high enough. In other words, I seek high BC through aerodynamic efficiency...
  7. J

    Effects of Rifling Grooves on Performance

    Gain-twist rifling was developed in the 1800's for shooting heavy cast or swaged lead-alloy slugs (subsonic bullets) at black powder velocities for which it works fairly well. I would restrict jacketed, lead-cored bullets to slower twist-rates where gain-twist is not needed. I cannot see...
  8. J

    Effects of Rifling Grooves on Performance

    RE: Oneshot's recovered 375 copper bullet fired from the gain-twist Bartlein barrel. It looks like the widths of the land engraving marks shown in the gas sealing rings increase by about 50 percent from bottom to top along the shank of the copper bullet. The helix angle started at 4.21 degrees...
  9. J

    Effects of Rifling Grooves on Performance

    This looks to be a monolithic copper-alloy bullet. The shear strength of the bullet material was a little too much for the bullet to twist quite as much as the helix angle increased in the gain-twist barrel. As I have said repeatedly, he need not have bothered with a gain-twist barrel for his...
  10. J

    Effects of Rifling Grooves on Performance

    My understanding is that for either solid lead-alloy black-powder-style bullets or for jacketed lead-cored rifle bullets, the gain twist rifling engraving marks on recovered bullet shanks look about the same as they would if fired from constant-twist barrels at the final twist-rate. In other...
  11. J

    Berger .375 solids on the horizon

    The most highly stressed steel around the chamber swell is the steel forming the chamber walls immediately surrounding the middle of the powder column in the loaded cartridge. That is why conformal piezoelectric pressure transducers are placed there. Al Harrell, retired mechanical engineer from...
  12. J

    Berger .375 solids on the horizon

    Yes, that is correct, George. Steel is very elastic with a modulus of elasticity (E) of 28.5 million psi for stainless alloys to 30 million psi for plain carbon-steel. I used 29 Mpsi which is about right for high-alloy steels like 4340 which is a great barrel steel. Yes, the bullet was engraved...
  13. J

    Berger .375 solids on the horizon

    The 246-gr and 250-gr bullets in my 338 LM example calculations have moved only 3.2 inches from their starting positions when they experience their peak base-pressure. The timing, bullet position, and percent of peak chamber pressure for this peak base-pressure event vary with caliber...
  14. J

    ELR bullet recovery

    My design goal was to increase the maximum supersonic range greatly, not to design a good subsonic bullet. Unfortunately, I don't know how to do both simultaneously. I expect the 375-caliber version of my bullet to stay supersonic all the way to the 2-mile targets at Whittington this year. Has...
  15. J

    ELR bullet recovery

    Those bullets were fired and recovered in several different firing tests using different powders. The clean undrilled bullet was fired with VV-N560, and the dulled bullets were fired with Alliant RL-25 which produces excess sulfides and dull the copper where it came into contact. No MS chrono...
  16. J

    Berger .375 solids on the horizon

    Here is an edited version of yesterday's paper on how copper bullets work in the rifle barrel compared to lead-cored bullets. I doubt you can find this information elsewhere. I tried to write this paper for riflemen as well as mechanical engineers to understand. I think this paper could be...
  17. J

    Berger .375 solids on the horizon

    Don't misunderstand, BAGW, I really want Berger or anyone else to build and market my bullet designs, or variations of them, successfully. I doubt that any CNC-turned copper bullet can be made from quality half-hard copper and sold for less. On the other hand, by insisting on "going it alone,"...
  18. J

    Berger .375 solids on the horizon

    I was granted a US utility patent (9,857,155 B2 on January 2, 2018) on a monolithic rifle bullet design which this new Berger bullet resembles to a rather startling degree. That design effort required 5 years of work. I offered my bullet design to the president of Berger a couple of years ago...
  19. J

    ELR bullet recovery

    Here is a picture of some of my 338-caliber monolithic copper ULD prototype bullets made by Dan Warner. The top bullet is un-fired for comparison. The other bullets were fired at about 3000 fps from my 10-twist Krieger barrel with conventional 6-narrow-land "square-cut" rifling. The bullets were...
  20. J

    Hyper Stabilized Bullets - Jim Boatright

    I decided next to try enlarging our bullet's rear driving/sealing band OD to groove ID plus 0.0006-inches, together with the minimum base drilling needed to aid in gas sealing. We will see what we can accomplish with pure copper on steel gas obturation before venturing into bullet/barrel...
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