Gain additional velocity by shooting prone ...

Discussion in 'Long Range Hunting & Shooting' started by FEENIX, Dec 2, 2018.

  1. FEENIX

    FEENIX Well-Known Member

    Messages:
    11,058
    Joined:
    Dec 20, 2008
    L:DL! I like experiments, especially when inquiring minds wants to know. :cool:
     
  2. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    ? Muzzle brakes operate after the bullet leaves the muzzle. They have no effect whatever on the bullet, recoil (before the bullet leaves the muzzle - edit), or velocity. Less recoil movement makes bullets travel faster, not slower, owing to conservation of energy. Abundant non-sequiturs here. But funny.
     
    Last edited: Dec 7, 2018 at 10:48 AM
  3. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    No no no - you need to lose weight so that you can run towards the target faster, increasing the energy of the bullets you shoot, and turning your .223 into a .458 Magnum.
     
    Last edited: Dec 7, 2018 at 8:39 AM
  4. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    Absolutely correct. Simple thought experiment: if the rifle is moving backwards at muzzle velocity, then the bullet will leave the muzzle at zero velocity and zero energy. Any lesser rifle rearward speed gradually increases bullet velocity. A rifle moving forward increases bullet velocity additively, up to light speed.

    So put a light on the back of your .22 and make it an elephant gun . . . (;-)
     
  5. adam32

    adam32 Well-Known Member

    Messages:
    1,179
    Joined:
    Nov 14, 2007
    Recoil also happens after the bullet leaves the muzzle...hence me being facetious about muzzle brakes making bullets slower...
     
    MudRunner2005 likes this.
  6. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    There is rifle movement before the bullet leaves the muzzle; there are ample high-speed videos that establish that. Bullet transit time down the barrel is about a millisecond long - plenty of time for the rifle to move backwards a tad. In a 1911, for example, the slide is moving back before the bullet is out of the barrel. A rifle barrel is also flexing before bullet departure.

    A muzzle brake can't affect the velocity of the bullet, because - unless the bullet is really loose in the barrel, and there's abundant blowby of gas - its effect is only on the gas exiting following bullet departure.

    A muzzle blast effect that changes muzzle velocity as measured downrange a bit could be a result of muzzle blast affecting the alignment of the bullet with the axis of travel, effectively changing the drag component on the bullet. The bullet's center of pressure and center of mass are not coincident, so there's a rotating moment around the center of mass that would be applied to the bullet by a ground-reflected sideways force. Unlike the case with a chronograph a few meters from the muzzle, however, I doubt it would show on a magnetospeed, because it measures speed before the drag could significantly affect velocity.

    A blast shield would most likely only affect the initial chronograph trigger caused by muzzle blast gases moving ahead of the bullet; the effect should be to show a lower velocity when a blast shield is absent, because the bullet would trigger the second chronograph sensor longer after the first sensor responded to the gas. That would depend on the sensitivity of the sensors to unburned powder, etc.

    An empirical test would be good, however, since in theory, theory and practice are the same - but in practice, theory and practice are often very different . . .
     
  7. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    Right - I should have been clearer when I said recoil; I meant recoil before the bullet leaves the muzzle. Actually, I wonder if the diverting effect of the brake could make a bullet slower - I've never seen any study done of the effect of the "push" from muzzle gas jet force against the base of the bullet. It is moving faster than the bullet, and has solids as well as gas within it. It accelerates like mad once the bullet is out of the way.
     
  8. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    A Magneto Speed would be unusable for this test, because it moves with the rifle. It would show no difference whatsoever. The only chronograph that would show a change resulting from rifle movement would be one decoupled from the movement of the rifle - i.e. a ground-mounted one.
     
    Last edited: Dec 7, 2018 at 5:58 PM
  9. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    I can't seem to edit the misspell of movement - I keep getting an error that says that my comment contains spam. ? Edit; tried a few hours later and the edit went through; but there's no option to delete this post.
     
    Last edited: Dec 7, 2018 at 6:00 PM
  10. NEMTHunter

    NEMTHunter Well-Known Member

    Messages:
    491
    Joined:
    Feb 16, 2014
    Thats why the MS would work. MV is MV.
     
    MudRunner2005 likes this.
  11. GeorgeS

    GeorgeS Member

    Messages:
    16
    Joined:
    Nov 26, 2018
    I don't follow. If you are trying to measure the velocity of the bullet relative to the muzzle, you have to have a reference frame. If the reference frame is moving with the gun, then it will show no change. For example, if a ground-mounted chronograph were moving towards the gun, it would show a higher muzzle velocity than if it were stationary. If you are trying to show that muzzle velocity decreases (relative to a fixed plane) when the gun recoils, you need a fixed plane to measure it against. The Magneto Speed is moving back with the gun. If it were moving back at 1,000 f/s, it would still show the same muzzle velocity, because the frame of reference is moving at 1,000 f/s.

    Edit: I didn't do a great job above; here's the thought experiment. The gun has infinite mass, so it doesn't move. The Magneto Speed doesn't either. It records the velocity of the bullet relative to the muzzle, AND to the reference plane perpendicular to the ground. Next, the gun and Magneto Speed have zero mass, so the bullet doesn't move. The Magneto Speed and the gun do. The Magneto Speed, however, measures the velocity of the bullet relative to the muzzle as, say, 3,000 f/s - as the muzzle moves away from the bullet. But the velocity of the bullet relative to the reference plane is zero. So what we want to know - the velocity relative to the reference plane as a result of gun recoil - is NOT measured by the Magneto Speed, which shows 3,000 f/s.
     
    Last edited: Dec 7, 2018 at 11:11 AM
  12. Capt RB

    Capt RB Well-Known Member

    Messages:
    970
    Joined:
    Dec 1, 2014
    The first movement is caused by the release of pressure on the bolt on a conventional firing pin/trigger sear/trigger. As Pressure builds it expands the vessel ie the brass to seal off then push the bullet. Then the torque induced by the bullet engaging the rifling will start the movement in a twisting motion arresting some of the rearward motion. But there are alot of things moving long before the bullet exits. The greatest amount of recoil is cause by the expanding gasses hitting the wall of atmosphere at the muzzle. This is the felt part and shows the most movement. Arresting that expanding gas with a device to divert and diffuse the amount that hits the wall at the end of the muzzle produces a reduction in reward movement.
    Some things that correct some of the movement.
    David Tubb's new DTR rifle uses a spring loaded bushing that holds the locking lugs to the rear against the surfaces. This helps keep the energy to drive the firing pin forward without the parasitic losses of a conventional system. Results in a faster lock time which equals a shot closer to the sight picture when the trigger was pulled.
    Twisting left hand vs right hand for a right hand shooter will twist the rifle into the shooter vs away. With a rifle mounted against the shoulder and into a cheek the nut behind the trigger can reduce some of the torque induced movement. This would help in a miniscule way to use more of that enrgy being expended to move the bullet forward vs wasted energy in the recoil process.
    Having a straighter case wall to grab the chamber walls will slow the rearward movement that a highly sloped case will.
    These are not picking up hundreds of fps. They gain .25% here .5% there etc etc. Put them all together and you see gains that can change your DA a point or 2 for your particular rifle. Inside of 1000yds most shooters couldn't see it if you told them. For the ELR guys picking up some consistency and speed for free just for doing things to the nth degree is why they do it.
    Minds are like parachutes they don't work when you don't open them. In some cases the results are quite catastrophic.
     
  13. Alex Wheeler

    Alex Wheeler Well-Known Member

    Messages:
    592
    Joined:
    Jul 5, 2017
    Well, theres very conflicting data, performed without moving the gun or chony and with ammo loaded to very high precision. Free recoil vs hard hold. No difference in speed. Now 20 fps by moving a chony I can believe.
     
  14. NEMTHunter

    NEMTHunter Well-Known Member

    Messages:
    491
    Joined:
    Feb 16, 2014
    In all honesty its very simple. Almost to simple. Thats why its hard to grasp when it's over thought. I am in no way saying you are stupid. I just feel you are over thinking it. I feel the point you are missing is this.

    If what the video shows is true. IF! Now think on this. The FPS loss is happening IN the barrel..... Not OUT of the barrel. Thats the only place the bullet will be loosing the velocity.

    So IF thats the case as its shown in the Video. Then the MS would be the best and most simple way to test IF it true or not.

    Nathan @ muzzle breaks and more and the Gentlemen that makes the Terminator breaks have the best setup to test the "theory" of loss prone or from a bench. Simple reason is they can control on the there test stands how much the gun move. Simply put they can make the gun so it cant move or consistently move freely a given distance.

    The true hardest part is having ammo with a ES of zero. But its not needed. just a consistent ES will do.
     
    Last edited: Dec 7, 2018 at 10:03 PM
    adam32 likes this.