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Recoil and Velocity Myths Debunked

Discussion in 'Shooting Related Threads' started by Paladin, Jan 15, 2010.

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  1. Paladin

    Paladin Well-Known Member

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    This is for all of the Newton's Laws of Motion absolutists that have posted here that recoil is solely dependent upon the weight of the projectile and its velocity versus the weight of the gun, with no regard to powder characteristics and how the velocity was achieved.

    Grab your January issue of the American Rifleman, go to page 55 to an article titled "Something For Nothing?".

    David Emary, Hornady's chief ballistics scientist has authored an article about their SUPERFORMANCE line of ammunition, specifically focusing on the powder and its characteristics, and has debunked many of the bantered about theory's of velocity and its relation to recoil that have been posted here.


    His findings that focused on "Relative Recoil Force" were very interesting and informative to say the least.
     
  2. goatskin

    goatskin TS Member

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    err, no. Hornady has not changed the laws of physics, and besides you are over-crediting Newton.

    THE <i>substantial</i> component of recoil is exhaust gases (and soot, cinders, clinkers, unburned powder, roots and insect parts) slamming against air outside the muzzle.

    In the recoil formulae, that is convered in the constant ... nominally 4000 (historical), but much closer to 2500 for shotgun (by testing observed v. predicted recoil).

    What Hornady has done is reduced exit mass and velocity somewhat by expelling less trash into the 'solid' column of air, ergo, dropping the constant, and, reducing actual impulse and momentum.

    Even the slowest shotgun powders are burned & consumed turning mass into energy in a few inches, unlike rifle powders.


    Bob
     
  3. short shucker

    short shucker TS Member

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    Hang on, this one could get fun.

    <a href="http://s299.photobucket.com/albums/mm301/ecshooter/?action=view&current=1hookchase.gif" target="_blank">[​IMG]</a>

    ss
     
  4. goatskin

    goatskin TS Member

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    <i>Hang on, this one could get fun. </i>

    Well ... It IS the dead of Winter, after all, and 8s v 7½s is stale and Tron is on vacation, so why not?


    Bob
     
  5. goatskin

    goatskin TS Member

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    re: recoil in a vacuum (prior post removed, apparently?)

    yep ... or mostly correct, anyhow. Rockets move in the space vacuum because 'fresh' gasses are pushing against 'old' gasses.

    You'll still have some post-exit recoil even in a vacuum, but I have no idea what the shape of the curve might be.

    If you were shooting in a high velocity wind-tunnel, you'd have less recoil - or more - depending on which way you were facing, too.

    There (theoretically) is less recoil on top of Mt Everest, too, than there in in Death Valley, also.

    The constant in the formula is an assumption, but it includes the whack of gas into a (for practical purposes) solid.



    Bob
     
  6. JerryP

    JerryP Active Member

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    Goatskin, "Rockets move in the space vacuum because 'fresh' gasses are pushing against 'old' gasses."
    Would you explain that please? Rockets don't have to push against anything to move. A force in one direction creates an equal force in the opposite direction.
     
  7. jim brown

    jim brown Well-Known Member

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    Now I know why you guys don't sign your names.

    jim brown
     
  8. Post  2

    Post 2 TS Member

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    By gosh I read it so it must be true. Post-2
     
  9. goatskin

    goatskin TS Member

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    Jerry, think abt that problem a second.

    I'm not trying to be funny, but if the gasses have nothing - and space is 'nothing' - to push against, how can there be movement?

    This is the same reason an airfoil WON'T work in space, there's nothing to work against to create lift. In order to create movement, thrust HAS to push against <i>something</i>.

    This is pure h.s. physics: equal & opposite, conservation of energy, momentum, etc.



    Bob
     
  10. goatskin

    goatskin TS Member

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    <i>how about we talk about 8-1/2s vs 7-1/2s or 8s vs 9s?????? </i>

    hmmm ... hard or soft?

    And why are we leaving out Steel?

    BTW, can you shoot Steel at the Grand at every bank? Or do they have a few plywood-covered banks?



    Bob
     
  11. Jack L. Smith

    Jack L. Smith Member

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    Jim Brown

    "Now I know why you guys don't sign your names"

    With mine & your's, why sign, nobody believes us anyway.

    jack smith
     
  12. halfmile

    halfmile Well-Known Member

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    The thrust of the expelled gases pushes against the object. Action & reaction. Gases go one way, object the other. We went to the moon in a vacuum, remember?

    geeeeez.

    HM
     
  13. Paladin

    Paladin Well-Known Member

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    "No, Hornady has not "debunked many of the bantered about theory's [sic] of velocity and its relation to recoil". Hornady cannot break the laws of physics."


    EE;

    My ieSpell program missed the "theory's", but maybe you are to uneducated and otherwise ignorant to read well. No where,,NO WHERE did I state Hornady changed any laws of physics. Period.. Comprehend? Both you and Waalkes need to read completely before opening your flaps.

    What they DID do is prove that the Newton's Laws of Motion absolutists (my term, since you don't comprehend well, EE) that have posted here that recoil is solely dependent upon the weight of the projectile (meaning shot charge only, since you don't comprehend well) and its velocity versus the weight of the gun, with no regard to powder characteristics and how the velocity was achieved, are wrong.


    Read the article, EE, then read it twice more. Feel free to post anything you disagree with, backed up with research.
     
  14. goatskin

    goatskin TS Member

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    <blockquote>Paladin: <i> What they DID do is prove that the Newton's Laws of Motion absolutists (my term, in case you can't comprehend, EE) that have posted here,that recoil is solely dependent upon the weight of the projectile and its velocity versus the weight of the gun, with no regard to powder characteristics and how the velocity was achieved, are wrong. </i></blockquote>

    Actually, they did no such thing. In fact they RE-PROVED Newton right.

    The reduced the mass of powder and reduced the volume and mass of ejecta slamming into a wall of air (thereby lowering the constant).

    Either of those things would reduce recoil. Newton said so.

    Hornady did both. Kudos to them for making a buck by re-discovering 500yr-old physics.

    C'mon Paladin, give it up.



    Bob
     
  15. goatskin

    goatskin TS Member

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    Rick ...

    1200 or 1250?


    Bob
     
  16. Paladin

    Paladin Well-Known Member

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    goatskin, listen. I am NOT saying Newton is wrong. Give it up.


    I am saying that those that have posted here that recoil is solely dependent upon the weight of the projectile and its velocity versus the weight of the gun, with no regard to powder characteristics and how the velocity was achieved, are wrong.

    You are including the powder in as the weight of the projectile. My intent is to show that differing powder DOES have an effect on recoil. The "absolutists" claim it's velocity and shot weight versus gun weight.
     
  17. goatskin

    goatskin TS Member

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    Paladin, I don't recall anybody on here saying 'projectile only', but if they did, they were both wrong & silly.

    That said ... a differing powder does NOT have any affect on recoil ... with a couple of standard presumptions, of course, like ± equal volumes and - like Hornady emphasized - reducing the volume of effluvium out of the muzzle.

    If there were, indeed, people here arguing that the weight of powder, wad and even the mass of the priming mixture were not part of recoil, then your slam of them is valid. (How hard you grip the gun matters more than most things, but that is ignored by almost all in all circumstances, but that is a digression.)

    Else you are creating a strawman and whaling the absolute stuffing out of it.

    What Hornady did was tinker with the constant, and I'm not sure even they realise that elemental fact.

    However & That Said ... that new 'discovery' applied only to rifle. In shotgun, anyhow, Hornady's discovery is meaningless, as all the powder is long burned before the first BB breathes air.

    Newton Rocks.


    Bob
     
  18. Paladin

    Paladin Well-Known Member

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    "projectile only" was not exactly stated, but the discussion was focused on varying powders having no effect on recoil, so the powder was assumed not to be included in the projectile.



    "In shotgun, anyhow, Hornady's discovery is meaningless, as all the powder is long burned before the first BB breathes air."


    Bob,,all long burned or not, the powder gas is still expanding, and there is still pressure at the muzzle, therefore there IS a reaction, and as you said, they "RE-PROVED Newton right". It is not meaningless in a shotshell.
     
  19. goatskin

    goatskin TS Member

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    eh ... obviously you paid more attention to ill-informed and/or strident people in the earlier hair-pullings than I must have as, in Neil's test, 'twas obvious that his PB bullets had more kick than his Red Dot bullets, because he used 2gn more PB than RD, and still nobody could tell one from the other without sniffing.

    Nah, it's meaningless in shotgun b/c peak velocity of the shot is somewhere in the barrel: 17-18" mebbe?, and while gas is still expanding, pressure is dropping fast, whereas in a rifle barrel length matters more b/c the powder is still burning and velocity is still increasing until it leaves.

    The recoil constant on a shotgun is what it is: pick a number, between 1800 & 2500, nobody can argue with you. Hornady, by getting a more efficient powder and not dumping a teaspoon of unburned-but-still-high-velocity powder into the (solid) air, Hornady reduced the constant for their new loads from 4000 to ... ?? 3800? 3500? less?

    The combination of a smaller constant and 15% less powder absolutely reduces recoil.

    Hornady did a good thing eliminating light & heavy manglum offerings, plus having an easier strain on their equipment not having to pack a blivet of powder, +, +, + ... AND shoots softer, too. I hope this cuts them a fresh fat hog in the ass, but it still has nothing to do with shotgun.

    Bob
     
  20. Paladin

    Paladin Well-Known Member

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    "but it still has nothing to do with shotgun."

    Well, that's open to debate. What we don't know is the pressure at the muzzle, but that's just part of it. A large frontal muzzle area must come in to play. Look at porting. Either there is an effect, or there isn't, and I believe porting has been proved to have an effect.
     
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