New case design!

Discussion in 'Reloading' started by Northman, Jan 20, 2006.

  1. Northman

    Northman Well-Known Member

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  2. royinidaho

    royinidaho Writers Guild

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    Looks interesting. Always good that someone is pushing for improvement. Somewhere along the line, thinking has got to change for advancement to be made.

    Keep on keepin' on! /ubbthreads/images/graemlins/cool.gif

    How about figgerin' a way to chamber a convergent/divergent nozzle instead of of the straight convergent we now have (Shoulder/neck). If I remember my steam turbine theory correctly, gas velocity is limited by the current arrangement. Just a little 'dry' Friday humor. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
     

  3. abinok

    abinok Writers Guild

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    Not even close to new guys...
    The 6mm Thermos Bottle was designed by M.L. McPherson in 1999. It is based on the shortened Lazzaroni Patriot case (or 416 Rigby). This “Thermos Bottle” design was to make a fat and short cartridge, able to handle 115 grs VLDs for 1K br competition. From a 30 inch barrel, it generates approx 3000 fps.
    Mr McPherson has patented the hemispherical shape BTW, and it may be just as well for he reports difficulty in forming cases. Somebody has a 45degree conventional shoulder 6mm on the shortened BMG case...
     
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Mcpherson is doing some interesting things but until a more user friendly design is come up with it will never fly with the public. Forming that case is a major project even for the most experienced wildcatters.

    It is good that he is testing the efficency thing though. We all get something out of this type of testing and it will show up in the future I believe in a more practical form.

    That said, look at the WSSM case, MUCH easier to form to a design like this then the Lazzeroni cases, probably better brass as well /ubbthreads/images/graemlins/grin.gif!! Hell of alot cheaper!!

    I am working on a competition type wildcat similiar to this but in 25 cal to offer better ballistics at 1000 yard comp. Should be out this summer I am hoping!!

    Kirby Allen(50)
     
  5. abinok

    abinok Writers Guild

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    [ QUOTE ]
    How about figgerin' a way to chamber a convergent/divergent nozzle instead of of the straight convergent we now have (Shoulder/neck).

    [/ QUOTE ]
    Roy... bad idea.
    The entire idea behind the DeLaval nozzle is to increase velocity of the ejected gas in open air. Restricting the exhaust side of a DeLaval nozzle inside a long tube like a rifle barrel results in condition known as the Bernoulli Lock Effect, or Krushnic Effect: This happens when the nozzle is recessed into a tube by more than one tube diameter. If so recessed, the cylindrical volume below the nozzle forms a secondary expansion chamber which allows the exhaust gasses to expand below atmospheric pressure before leaving the tube. A multi-stage rocket that ejects its booster motor, but not the airframe, is a perfect example. Very damaging; it almost always destroys the lower body airframe beyond use. Named for Richard Krushnic, the rocketeer who characterized the effect in the late '60s.
    Seen and experenced it myself more times than id care to admit. It SUCKS Literally! /ubbthreads/images/graemlins/smile.gif
     
  6. 4ked Horn

    4ked Horn Writers Guild

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    I didn't read into the information but the picture in the link seems to indicate the designer is going for a case that promotes forward ignition of the powder or at least a focused combustion point. The drawing does not include any vectors for the dispersal or difusion of the primer blast due to the powder in its way so I'm not sure it is an accurate drawing. Mr. Gibbs experimented with forward ignition and even devised a way to modify centerfire cartridges for it. It seemed to work reasonably well and was easier than trying to form these semi circular cases.
     
  7. Northman

    Northman Well-Known Member

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    He is working with Norma to produce this..

    On the webpage he states the brass will be out late 2005.. now it looks like somtime in 06?