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recoil v accuracy

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  #15  
Unread 07-04-2011, 04:20 PM
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Re: recoil v accuracy

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Originally Posted by WildRose View Post
The only forces working to push the rifle backward at that point is the force of the bullet pressing on the air ahead of it in the barrel and the tiny fraction of hot gasses that are not contained behind the bullett.

Once the bullet clears the end of the barrel then in effect the barrel is acting like a rocket motor driving back the rifle in the opposite direction.

That is why a good muzzle brake is so effective at reducing felt recoil and muzzle flip.
Well said Wild Rose. Until the bullet leaves the barrel it is a "closed system" and the effects generated by the expanding gasses on the outside world is VERY minimal as you pointed out.

I'm just a retired electronics engineer, but we had this same discussion on here a couple of years ago. A couple of guys who are real physicists weighed in on the subject and explained the closed loop system of of a rifle barrel / bullet. I think the orginal question then revolved around if there was any difference in velocity between a bullet fired from a tightly held rifle or one allowed to "free recoil". Different question, but the real world physics is still the same.

The bullet is GONE before recoil starts to push the rifle around.
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  #16  
Unread 07-04-2011, 04:26 PM
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Re: recoil v accuracy

OK, I can maybe buy into the rearward recoil being minimal untill the bullet is gone or nearly gone, but I am visualizing torque as being totally different.

I would think that as soon as the bullet engages the rifleing, then the equal and opposite effect begins and the rifle tries to torque counter clockwise (looking from the rear).

No matter if it's torque or rearward movement or rearward movement caused by reactive torque (a screw type effect if you will), the rifle is in fact moving some before the bullet leaves the barrel............Makes the most logical sense to me anyway.
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Last edited by SBruce; 07-04-2011 at 04:29 PM.
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  #17  
Unread 07-04-2011, 06:53 PM
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Re: recoil v accuracy

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Originally Posted by SBruce View Post
OK, I can maybe buy into the rearward recoil being minimal untill the bullet is gone or nearly gone, but I am visualizing torque as being totally different.

I would think that as soon as the bullet engages the rifleing, then the equal and opposite effect begins and the rifle tries to torque counter clockwise (looking from the rear).

No matter if it's torque or rearward movement or rearward movement caused by reactive torque (a screw type effect if you will), the rifle is in fact moving some before the bullet leaves the barrel............Makes the most logical sense to me anyway.
No, torsion is restricted by the same principles of physics.

Until the bullet exits, all the forces are acting on the bullet itself.

The torquing effect is felt because the gasses escaping the barrel are following the path created by the lans and grooves of the rifling creating a vortex of gasses at the barrel as they exit.

As long as the pressure vessel remains sealed, the forces are simply driving forward. Energy always seeks the path of least resistance, and twisting a small bullet is far easier than twisting a rifle that out weighs it by many, many times over.

Again, with a proper muzzle brake you will notice little to no torque effect at all.
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  #18  
Unread 07-04-2011, 07:56 PM
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Re: recoil v accuracy

If recoil does not begin until after the bullet leaves the barrel then why does how you hold the rifle matter at all?

You have a bullet of some mass accelerating from 0 to 3000 fps. As soon as that bullet begins to accelerate Thare is an oppsite and equal reaction. The initial action is the expansion of the gasses from the burning powder, the equal reaction is the bullet accelerating forward, and the oppsite reaction is the rifle moving backward.
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  #19  
Unread 07-04-2011, 10:14 PM
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Re: recoil v accuracy

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Originally Posted by coonhunter View Post
If recoil does not begin until after the bullet leaves the barrel then why does how you hold the rifle matter at all?

You have a bullet of some mass accelerating from 0 to 3000 fps. As soon as that bullet begins to accelerate Thare is an oppsite and equal reaction. The initial action is the expansion of the gasses from the burning powder, the equal reaction is the bullet accelerating forward, and the oppsite reaction is the rifle moving backward.
Until the pressure of the expanding gas exits the barrel that equal and opposite reaction is contained within the pressure vessel.

The only force exerted ahead of the bullet are the air pressure (environmental as in barometer) and the tiny fraction of gas that gets around the bullet. Thus there is nothing to push the rifle back other than a tiny, tiny amount of air pressure.

Notice in this video when the recoil shows it's effect.


The main reason it matters how you hold the rifle is to get properly alinged and steady on target, keep yourself from flinching, reduce felt recoil against your shoulder and to remain closer to on target so you can see your bullet impact and make quicker follow up shots.

With a decent muzzle brake you can set your rife on a bipod and the butt sitting on sand bags and fire a nice tight group with only your finger in the trigger and no other contact point against your body.
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Last edited by WildRose; 07-04-2011 at 10:18 PM.
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  #20  
Unread 07-05-2011, 08:44 AM
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Re: recoil v accuracy

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Originally Posted by RDM416 View Post
Well said Wild Rose. Until the bullet leaves the barrel it is a "closed system" and the effects generated by the expanding gasses on the outside world is VERY minimal as you pointed out.

I'm just a retired electronics engineer, but we had this same discussion on here a couple of years ago. A couple of guys who are real physicists weighed in on the subject and explained the closed loop system of of a rifle barrel / bullet. I think the orginal question then revolved around if there was any difference in velocity between a bullet fired from a tightly held rifle or one allowed to "free recoil". Different question, but the real world physics is still the same.

The bullet is GONE before recoil starts to push the rifle around.
I don't care when you think recoil starts. I said that the equal and opposite reaction starts when the bullet moves the first micron. It is really stupid to think that moving an object doesn't require force because it is inside a pipe. If your idea was correct my semi auto 12 gauge and pistols would not work. They are spring actions - not gas operated. The action starts to come back as soon as the bullets or shot moves.
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Last edited by budlight; 07-05-2011 at 09:04 AM.
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  #21  
Unread 07-05-2011, 09:25 AM
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Re: recoil v accuracy

Budlight,

I understand it does not seem follow the "equal and opposite" reaction law of physics, but it does. In order to understand the principal that "Wild Rose" brought up, you have to know what a "closed loop system" is in physics.

Until SOMETHING moves external to the barrel, the bullet, barrel, case......... are in a closed loop. When the bullet leaves the barrel, the closed loop is OPENED and all the recoil factors begin. As Wild Rose pointed out there is a tiny amount of air in the bore that is being pushed out the end of the bore in front of the bullet and there would be the tiny amount of expansion of the barrel steel. Those are EXTERNAL and keep the system from being a total "closed loop", however the effect of those things are so small as to not matter.

It has been 30 years since college physics for me so I am a little rusty here, but if you are interested in understanding, look up "closed loop systems" in a physics text.

After all that........ I will still maintain my statement that the recoil of the rifle does not affect it's accuracy, only how we react to it.

It's been fun, and a good discussion, and will admit I certainly could be wrong. Not trying to be the resident physics expert here because I'm not.
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