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  1. J

    A Problem Unique to Long-Barreled Rifles

    First, let me say that I have significantly expanded my spreadsheet calculations, specifically to include the first seven modes of transverse vertical plane shear-wave vibrations. This study is based upon a new approach I came up with to consider the the recoil torque applied to the barrel to be...
  2. J

    A Problem Unique to Long-Barreled Rifles

    For any caliber smaller than about 0.400-inch, the size of the hole makes very little difference with target barrels.
  3. J

    A Problem Unique to Long-Barreled Rifles

    I have redone the analysis of the 50 BMG example considering all possible barrel vibration modes, and the results are the same for that long 44-inch barrel. The best estimate of the downward muzzle speed at bullet exit is 4.75 ips. The muzzle is moving upward from the start of motion at 1.008...
  4. J

    A Problem Unique to Long-Barreled Rifles

    Speaking of exact opposites, I heard back from David Tubb who has researched this topic thoroughly that his observational findings are the reverse of what I just published. What that tells me is that I have oversimplified the problem of muzzle motions for clarity in explanation. All of the...
  5. J

    A Problem Unique to Long-Barreled Rifles

    I made PDF's of the Figures and what the spreadsheet would look like. The active Excel workbook will have to be emailed unless it perhaps can be posted here as a Resource.
  6. J

    A Problem Unique to Long-Barreled Rifles

    I was asked several years ago by David Tubb to explain ballistically why crosswinds favored riflemen shooting barrels made with twist direction matching the crosswind direction--L to R winds favoring LH twist barrels, and vice-versa. I could find nothing in aeroballistics showing any asymmetry...
  7. J

    22LR twist rate

    Yes, the quicker twist-rate directly slows the initial coning rate of the bullet which has the effect of increasing the integration time interval over which aerodynamic jump accumulates. I was experimenting with round-based (convex) bullet designs which increased bullet yaw and yaw-rate...
  8. J

    Progress in Developing Copper ULD Bullets

    After getting the base drilling of our monolithic copper 338-caliber bullets right, we have seen many 5-shot groups with extreme spreads of muzzle speed around 4 fps. That is in 338 Lapua Magnum using VV N570 and Federal 215 primers. We saw this in both Schneider P5 7-inch twist and Bartlein 5R...
  9. J

    Progress in Developing Copper ULD Bullets

    Centerfire rifle barrels are bent upward by their attachment to the action during recoil. This initial displacement is not quite what I mean by a "vibration." It is the externally forced initial distortion which causes subsequent standing wave vibrations after that external force ceases. Just...
  10. J

    Progress in Developing Copper ULD Bullets

    No, JB.IC, this particular muzzle brake might have been designed in 1944 by somebody at Winchester, but does not seem to have been patented. While mentally designing one quite similar, I ran across this one example on the "EXP" marked Winchester Automatic Rifle in 30-'06 from the collection at...
  11. J

    Progress in Developing Copper ULD Bullets

    While I was mentally imagining this design, I saw the MB attached to the barrel of the prototype Winchester Automatic Rifle (WAR) in the Cody Firearms Museum collection. That rifle was successfully demonstrated to the Army in December of 1944, but dropped completely after VJ-Day. The exit nozzle...
  12. J

    Progress in Developing Copper ULD Bullets

    Thanks for the reference, Alex. Somehow I missed that report on DTIC. Figure 10 seems to support my rather conservative choices of a 7.5-degree BT of 0.70-calibers in length. Ten thousand calibers of travel would be 85.6 yards for a 30-caliber bullet. The critical slow-mode (gyroscopic...
  13. J

    Progress in Developing Copper ULD Bullets

    A really good point, Alex. I do seek a higher BC bullet design which retains its dynamic stability throughout its flight. To that end, one of my earliest bullet design criteria was to maintain a sharp angle at the rear corner of the 7.5-degree boattail of 0.7-calibers in length. I reasoned that...
  14. J

    Progress in Developing Copper ULD Bullets

    Sure, Theis, you could use four struts instead of three just as long as each strut has a knife edge pointing toward the axis of the bore. Keep in mind the tremendous strength needed to withstand the repeated muzzle blast forces. The gap between the crown of the muzzle and the aperture of the gas...
  15. J

    Progress in Developing Copper ULD Bullets

    I have found the muzzle brake which I had been mentally designing to provide an adequate counter-recoil impulse without destabilizing the bullet in yaw. It was shown by Ian McCollum (ForgottenWeapons.com) in his August 1, 2016, program on the Winchester Automatic Rifle, a late WWII replacement...
  16. J

    Progress in Developing Copper ULD Bullets

    I looked up the Terminator and APA brakes mentioned, and yes the ports on the Barrett MRAD brake are much larger, which was what I wanted for testing. In fact, it is hard for me to see why the outer (front) pair of ports are even needed for the MRAD brake. I will probably cut them off after...
  17. J

    Progress in Developing Copper ULD Bullets

    You are correct, Max, that the harmonic standing wave transverse vibrations of a center-fire rifle barrel occur after the bullet has departed, unlike with long 22LR rifle barrels. These transverse barrel distortions are primarily driven by the rifle's recoil reaction forces which are eccentric...
  18. J

    Progress in Developing Copper ULD Bullets

    Good thinking, except for the rocket nozzle attachment idea. I am not so concerned about any destabilization happening to the bullets beyond the frontmost metal parts attached to the muzzle. I believe the main destabilization problems to solve first are due to (1) high speed gas flow through any...
  19. J

    Progress in Developing Copper ULD Bullets

    I think that could work, gnochi, but why bother? The really high evacuation rate brakes are loud as hell, but they do work well at producing counter-recoil force. I am thinking that a simple horizontal-firing T-style single chamber brake (like a glorified pipe Tee) might be best for launching...
  20. J

    Progress in Developing Copper ULD Bullets

    The good news is you will see higher average BC's than others shooting those copper bullets from slower-twist barrels. Crosswind sensitivity will be amazingly low and maximum supersonic ranges will be greatly extended. The bad news is that you are going to be really stressing your rifle...
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