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Thread: 9 mm recoil: 147 gr or 124 or115?

  1. #11
    Quote Originally Posted by Squib308 View Post
    Momentum is conserved
    Kinetic energy is not conserved

    Assuming blast and sound are not considered, physical “Recoil” is related to momentum, which is why very fast lighter projectiles will generate far less “recoil”. In terms of handguns it gets more complicated due to physical characteristics of the pistol-operator interface, slide mass, recoil springs, hammer spring or other factors than can either temporize or “absorb” the forces. Time is also a huge factor…the same force over a shorter time period will be perceived as much stronger although by Newton’s 3rd law it’s the same.
    In this post, you're talking about free recoil and felt (perceived recoil), mixing the two in a confusing manner. Free recoil is quantifiable. Though related, they aren't the same. Felt recoil, not so much. Felt recoil is very much a matter of opinion of the shooter.
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  2. #12
    Site Supporter JSGlock34's Avatar
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    There's a reason why Federal built their popular 9mm Syntech Action Pistol loading around a 150 grain bullet.



    This round is popular in USPSA; besides competition I've also used it when instructing recoil sensitive shooters.

    Note that there are a number of Syntech loadings now; the Action Pistol load is particularly geared for USPSA shooters looking to satisfy Power Factor requirements. Some Syntech loads are designed to matched defensive ammunition, and obviously these will not have the same recoil characteristics.
    "When the phone rang, Parker was in the garage, killing a man."

  3. #13
    To the OP: If the box label or catalog listing shows bullet weight and velocity, multiply them to get Power Factor. Lower Power Factor, less recoil as a general thing.

    You have to get deeper into the physics to see what is going on when two loads of the same Power Factor or computed recoil have different "felt recoil." For which I am not much qualified, but I know there is stuff going on inside the gun. I think one contributor is bullet acceleration. A heavy bullet off to a slow start and getting up to a lower muzzle velocity appears likely to disturb the gun less. There may even be a factor for change in acceleration as powder burns up and friction increases, sometimes called "surge".

    And while the mathematics ignore muzzle blast and flash, the human nervous system does not.
    I saw that last week. I had sluggish function from my 124 gr Minor power factor reloads in one gun, so I splurged on some 115 gr econoball which worked better. The loud bang, supersonic crack, and bright flash were a jar.
    Code Name: JET STREAM

  4. #14
    Member randyflycaster's Avatar
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    Folks,

    Thanks so, so much for all your great answers. Very helpful. I've learned a lot.

    Randy

  5. #15
    Site Supporter 1911Nut's Avatar
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    In the context of 9mm . . . . . what is this "recoil" of which you speak?

    Sorry, I couldn't help myself.

  6. #16
    Member JMS's Avatar
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    I don't think that that's completely out of line; I think most of the folks who talk of 9mm perceived recoil overfocus on it. The idea that one should attempt to cultivate a certain level of insensitivity to recoil has value. "Climate's what you expect, weather's what you GET." Perceived recoil can wander between lots, altitude, temperature, along with all the other nitnoid crap *ahem* I mean data that folks track.

    ...and I say that having deliberately chosen to zero everything I have to 147gr HST (147gr ball to practice/train/compete) across the board due *at least in part* to 147gr typically (not universally) having less perceived recoil...plus the longer projo having better engagement with the rifling, which typically provides for better accuracy in my guns.

    ...and because, in the (still ongoing, to me, with more to come now that we're seeing imports banned) drought, I snapped up soooo much because-I-could-get-it good 124gr because having reasonable quality ammo to shoot trumps what it's perceived recoil may be. I just eat the POI shift, which is typically >1"@25yd for mine. Insignificant.

    Hells, when I was shooting 124gr exclusively, I'd practice with hotter ammo...as stated, non-US brands like Magtech and S&B tend to use the NATO recipe...and shoot comparatively cheesy-poof-recoil US stuff for scored events.

    We could really start baking noodles, and bring up comps....

  7. #17
    Quote Originally Posted by MistWolf View Post
    In this post, you're talking about free recoil and felt (perceived recoil), mixing the two in a confusing manner. Free recoil is quantifiable. Though related, they aren't the same. Felt recoil, not so much. Felt recoil is very much a matter of opinion of the shooter.
    What’s the difference between momentum (m x v) and “free recoil” ?

  8. #18
    Quote Originally Posted by Jim Watson View Post
    And while the mathematics ignore muzzle blast and flash, the human nervous system does not.
    I saw that last week. I had sluggish function from my 124 gr Minor power factor reloads in one gun, so I splurged on some 115 gr econoball which worked better. The loud bang, supersonic crack, and bright flash were a jar.
    Which is why I always have new shooters double up on hearing protection if possible. Decreasing noise can decrease perceived recoil.

  9. #19
    Quote Originally Posted by Squib308 View Post
    What’s the difference between momentum (m x v) and “free recoil” ?
    M x V leaves out a lot of important information, such as mass of firearm, mass of powder charge and velocity of gases exiting the muzzle.

    Launching a bullet launching a 147gr bullet @ 1100 from a ten pound firearm is gonna have less free recoil than it would from a 5 pound firearm.
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