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Does Presure = Recoil

Discussion in 'Shooting Related Threads' started by max trap, Jul 16, 2009.

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  1. max trap

    max trap Member

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    Lets say your loading 17.2 - 17.5 grains of powder for somewhere right at 1150 ft per sec. Differnt hulls and differnt wad combinations change published pressure even though powder is within a couple tenths. My question is does the higher pressure with the same velocity change felt recoil ?
     
  2. jimrich60

    jimrich60 Member

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    Short answer is no, since pressure is exerted in all directions. Not merely backwards. Recoil energy is determined by weight of ejecta (wad, shot) and velocity. Mitigating recoil energy (that is soaking it up) is the weight of the gun. That is for actual recoil energy. Felt or perceived recoil is controlled by many things-actual recoil energy, gun fit, etc. For instance, stock design can result in a "hard kicking gun" even though actual recoil might be the same as another gun which "feels soft".

    Jim R
     
  3. yansica1

    yansica1 Member

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    To all intents and purposes yes. A high pressure reading almost always equates to higher recoil. This could be twisted around for a few days, but as I said.................

    ps. you`d have a job finding a hot load with low pressure readings and hot loads kick.
     
  4. AveragEd

    AveragEd Well-Known Member

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    I'm not disagreeing with Jim but I recently performed a little experiment that may suggest otherwise.

    I loaded two boxes of STS hulls with an ounce of shot, Remington TGT-12S wads, PB powder and Federal 209A primers. I also loaded two boxes with the same recipe except with Remington 209P primers and, as called for by IMR's data, 0.5 grain more powder. In fact, I added 0.7 grain as that's what my next-size-larger bushing dropped. I shot the boxes in alternating order by primer type and the Remington-primed shells felt slightly softer on my shoulder. The recoil amount, as nearly as I could tell, was the same but the recoil of the Federal-primed shells felt sharper while that of the Remington-primed shells was less abrupt.

    IMR's data lists the pressures of those two recipes as being 400 psi higher with the Federal primers, so does that mean that pressure really does affect recoil?

    Ed
     
  5. Neil Winston

    Neil Winston Well-Known Member

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    No it doesn't Ed. The fact that the test was not "blind" means it doesn't mean anything.

    Neil
     
  6. zzt

    zzt Well-Known Member

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    Blind test or not, that's what I feel as well Ed. The pressure difference cannot affect actual recoil. I don't believe it can/will affect perceived recoil. It is the difference in primer types, IMO, that causes the difference in perceived recoil.

    Federal 209A primers are the hot particle type, whereas STS209 and W209 are hot gas type. Hot particle primers really get things started fast, and the difference in the timing of the recoil pulse is what I think you feel. It's the same as fast vs. slow powders and perceived recoil.
     
  7. Neil Winston

    Neil Winston Well-Known Member

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    Sarge, I don't have my books with me, but if you look at the last part of the article in Hatcher's notebook you cite, the recoil one, and do the suggested math with a trap shell, you will get a number like 4%, not the 30% you cite. He warns that the general correction factor for gas expansion used for rifles is too high and the one that squares with experimental results is more like 1.2.

    This rather low figure puts a limit on how much porting in barrels could possibly reduce recoil.

    In my double-blind experiment, neither I nor the second subject could tell the difference between shells loaded with a certain charge of Red Dot or a charge 8% larger.

    Neil
     
  8. Neil Winston

    Neil Winston Well-Known Member

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    For those who are willing to accept the speed of gun recoil as "recoil," the link above answers the question posed by the title of this thread.

    For those that don't, the world of experiment is wide open for them to prove their point, as I believe I have mine.

    Neil
     
  9. timb99

    timb99 Well-Known Member

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    "does the higher pressure with the same velocity change felt recoil?"

    The key word here is "felt recoil."

    Anybody can say anything and claim felt recoil.

    If you are talking about true recoil in accordance with the laws of physics? No.
     
  10. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Chamber pressure is measured in the chambers as the hull is in the beginning stages of opening if I interpret this correct? If so, would the velocity of the charge in that very beginning stage have any effect on the forward barrel pull? Might that be one of the factors involved with the felt feel some claim? We know from using the numbers with a very fast burning powder the pressure spike is very sharp all at once in the hull. Less with a more progressive powder which may burn completely within several inches of barrels after ignition. Using one chamber pressure measuring device which only measures pressure within the chamber itself may not tell a complete story as far as pressure farther along the burn path after the hull has expelled most of the shot charge?

    If we left a hinge pin out of a single barrel, which powder would propel the barrel forward most,fast or slow burning powders? This may be getting into the felt area that some feel rather than chamber pressure itself? Using conventional methods at hand now won't answer that question in my view. Could the answer be in that forward pull difference between the two? I'm gonna guess it may be. Different starting velocities but the same at the barrel end.

    Hap
     
  11. timb99

    timb99 Well-Known Member

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    I guess I go back to Neil's post on another thread.

    The time it takes for ignition to occur and for the ejecta to leave the muzzle is about 0.0035 seconds.

    In that time, your gun has barely started to move back, and probably hasn't moved enough to start to crush the fabric of your shirt, much less your recoil pad.

    I have a heck of a time believing that the differences in interaction in that short time between powder A with pressure X versus powder B with pressure Y, both with the same ejecta speed and weight, can be discriminated by even the most recoil sensitive of our ranks.

    They claim they can.

    It would take a well-designed blind test with carefully crafted shells to say for sure.
     
  12. John Thompson

    John Thompson TS Member

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    Felt recoil is much different with 2 loads which are assembled with identical components when the powder is changed. Compare chamber pressures with 700X versus IMR 4675 both loaded for 1200 fps. The felt recoil is much softer with the IMR.

    For another fly in the ointment, often loaded paper hulls exhibit lower felt recoil than first time reloads in plastics when loaded with factory components, for the same velocity.

    The major component is gun fit, in my opinion. Being left handed, I became very recoil concious prior to having a stock fitted.
     
  13. ivanhoe

    ivanhoe Well-Known Member

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    It is about to ask the author of this thread are you referring to actual recoil or Felt recoil? There is a difference between the two. So which is it max trap?

    Bob Lawless
     
  14. Baron23

    Baron23 Well-Known Member

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    Its not the speed of the payload that matters, its the acceleration that will result in Newtonian based opposite effect, i.e. recoil.

    Chamber pressure is not a direct measure of payload acceleration/speed of gas expansion from powder burn. I'm sure there are ways to increase total pressure from a slower burning powder/slower accelerating payload. But as a borad rule of thumb, yes.
     
  15. slic lee

    slic lee Active Member

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    Most of you have a lot to learn about gunpowder. It does not burn and/or react like you think it does. Gunpowder is NOT LINEAR!
    Those who think that all gunpowder pressure curves come to a sharp peak at max burn are wrong even though some do.
    Because you add .3 of a grain of gunpowder to a load does not mean there will be a change in pressure, a change in velocity or any change at all, sometimes nothing will happen, gunpowder is not LINEAR.
     
  16. goatskin

    goatskin TS Member

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    Sarge, if you'll replace the 'k' (be it 4000 or 4700) with Mv * 1.30 (±.05), then calculated Ir & Rv and observed Ir & Rv are pretty close.

    Admittedly, that has a healthy dose of pencil engineering, but so do other parts of the basic, classic formula when it comes to measuring factors that are hard to measure.

    Hatcher, Greenhill and Forsythe are still gods.


    Bob
     
  17. spitter

    spitter Well-Known Member TS Supporters

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    Recoil is a result of weight of the ejecta, speed of the load offset, by the weight of the gun. There have been previous threads on this very subject. But pressure is not a variable in any part of the equation...

    Respectfully offered,

    Jay
     
  18. highflyer

    highflyer TS Member

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    If you get the lowest recoiling powder with low pressure and with the right choke constriction and shot size, you will have a very soft recoiling load.
     
  19. timb99

    timb99 Well-Known Member

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    Hmmm.

    Someone please explain why my .410 loads, upwards of 12,000 psi, are much softer recoil than my 8,600 psi singles loads?
     
  20. PerazziBigBore

    PerazziBigBore TS Member

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    No.. but there are many other variables that can influence recoil.. Time.. being a big one..
     
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