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Pressure vs Efficiency, Clean Burn?

Discussion in 'Shooting Related Threads' started by WNCRob, Sep 16, 2012.

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  1. WNCRob

    WNCRob Member

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    Is there an optimal pressure range to get good, clean, efficient ignition? Any benefit to favoring lower-pressure loads, e.g 7500psi vs. 10,500psi for a given velocity?

    WNCRob
     
  2. goatskin

    goatskin TS Member

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    The short answer is nah, not especially, and it depends. Pick one or more.

    Some powders are inherently dirtier than others, but for each powder, there is a threshold pressure that will 'burn as clean as it will ever get' and higher pressure beyond that threshold does not burn any cleaner.

    And 'clean' is relative, too. Some powders leave a clean barrel and grimy hull. Some leave a clean hull and a coal mine in the tube.

    Bob
     
  3. shrek

    shrek Active Member

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    some powders will get blooper prone at lower pressures and some don't seem to.
     
  4. luvtrapguns

    luvtrapguns Well-Known Member

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    For years I loaded SR 7625 powder in an RXP hull. Recipe straight from the Lyman Book. Seems like I remember pressure was less than 6000 PSI. This was a 1 1/8 oz load @ 1145 FPS. With the Magnum Shot I felt like I had a better load than Factory New. Marc
     
  5. oskerspap12

    oskerspap12 Active Member

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    We loaded Promo for a while,and found that it burned much cleaner at the high end of its pressure scale,but thats just one powder........do some testing(if you reload),and awnser the question for yourself.

    D.P.Reynolds
     
  6. 3357

    3357 Member

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    Red Dot burns much cleaner over 8,000 psi than under it, for me anyway.
     
  7. shot410ga

    shot410ga Well-Known Member

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    Try Clays. It's the cleanest stuff I've ever loaded at any pressure.
     
  8. jhoward

    jhoward Member

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    If you shoot an auto, don't shoot low pressure Blue Dot loads!
     
  9. wayneo

    wayneo Active Member

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    If you look at all the reloading data, shotshells, rifle and handgun, they all have a lower and upper limit for the powder, weight of ejecta, primers, cases, etc. With shotguns we are not punching paper, but want a uniform pattern, right?

    I like what D.P. said. The more complete powder burn you have, the more consistent your patterns will be. Load some up and put it on paper. JMO

    Wayne
     
  10. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    The goal is to find a load that does consume the powder charge for consistant pressures and velocities. Once there, the SD numbers come down also meaning you have a consistant balanced load that performs almost the same shot to shot.

    Easier said than done too!

    Hap
     
  11. mike campbell

    mike campbell Active Member

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    IME, if you test (chronograph) often enough, you'll find that it's really not all that difficult to find recipes that will deliver extreme spreads < 40 fps and SD's in the 10-15 range....in other words, the equivalent of premium factory loads. And I'm speaking of a test of 10 rounds pulled at random from a 500-rd run on a progressive press. The flip side of that is, you should never settle for less.

    I've been testing my Old Favorite a couple times a year for nigh onto 10 years and it consistently beats the above stats, year in and year out.

    Heck, I load a 16ga favorite on a 9000G that runs +/- 10 fps with single digit SD's ....and it uses a 20ga wad!

    I have an internet pal that worked in a ballistics lab and he's fond of saying "Good 12ga target recipes are a dime a dozen."
     
  12. Shooting Coach

    Shooting Coach Well-Known Member

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    I prefer to load a minimum of 9000 PSI and a maximum of 10,000 PSI with shot shells.

    The deal breakers are usually the 28 and 410, but with several new powders, this can happen with them.

    For those who load the 410, you MUST try Alliant's 300MP. WOW! 1300 fps at 10,000 PSI.
     
  13. leadvail

    leadvail Member

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    Winchester says that their Super Handicap powder is the same one they use for their handicap loads.

    Looking at the load from them using their components, PSI is 11,300 for 1255 fps for the AA handicap load...

    So if your worried about using high psi loads, don't shoot new ones.

    You"ll wear your gun out more opening and closing it.

    People are the same when driving down the interstate highway at 55mph and the speed limit is 75mph, they feel we are hotrodders.

    Efficiency works for me. I get more consistent loads at higher pressure and long hull life also. Bob



    Bob
     
  14. Franktri

    Franktri Member

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  15. Shooting Coach

    Shooting Coach Well-Known Member

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    Dear Bob

    The factory has a huge advantage. They are using NEW hulls. We are, at least I am, using range pickup hulls that have been fired in who knows what kind of gun with the occasional over sized chamber.

    Resizing will weaken the case head. Fed GM hulls, among other types, have a paper thin case head. I have seen several of them fail, even new ones, and break ejectors on O/U's.

    Makes a difference.
     
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