bullet above bore's axis...?

A

Alaninga

New member
I know for all 'practical' physics that a bullet drops below a bore's axis as soon as it leaves the barrel. IF a wind [strong?] is coming from the right, and the bullet is spun in a right handed twist bore, will it rise above the bore's axis a small amount? Or will the right crosswind's effect only 'slow' it's fall compared to a 'no wind' shot?
: )
Really, probably discussed a million times, but I wasn't listening :)
 
Bullets go above the bore's axis for quite a while until it reached the point blank range which on some cartridges can be quite far like 200+ yds
 
There is no reason a bullet will ever fly higher than the barrels axis In my opinion. I think people misunderstand this because of the fact that the scope is pointed downward in relation to the centerline of the barrel, so the bullet flies upward compared to the view through the scope, but the bullet never flies higher than the bores axis. As far as the couriolus effect, I would think the bullet may drop less than without the super strong crosswind, but still never have a reason to rise above the bore.
 
Dusty Stevens said:
Bullets go above the bore's axis for quite a while until it reached the point blank range which on some cartridges can be quite far like 200+ yds
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So, you are saying that if the bore axis is horizontal, parallel with the ground, disregarding the curvature of the earth, a fired bullet will rise above that horizontal line?

Because, I'm guessing that was the OP's question.

I always thought the line of sight was straight, and the barrel is tipped up so the bullet will arc up, then down into the target at the point of aim, and the bullet rises above the line of sight, but not the center of the bore line.....
 
The reason bullets arc or rise is due to recoil. Since the stock is below the action's thrust line, the barrel recoils up and back. That causes the path of the bullet to go above the original sight plane (ie, muzzle tilt). Gravity is a constant and we all know the impact of that variable.

-Lee
www.singleactions.com
 
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Alaninga said:
I know for all 'practical' physics that a bullet drops below a bore's axis as soon as it leaves the barrel. IF a wind [strong?] is coming from the right, and the bullet is spun in a right handed twist bore, will it rise above the bore's axis a small amount? Or will the right crosswind's effect only 'slow' it's fall compared to a 'no wind' shot?
: )
Really, probably discussed a million times, but I wasn't listening :)
Click to expand...

Alaninga,

I assume your question relates to a wind from right to left on a right hand twist barrel seems to push the bullet higher on the target relative to no wind. This has to do with the gyroscopic forces of the spinning bullet. The nose of the bullet turns into the wind and upward creating lift. If you really want to know more about it here is a link to some great information on the subject. http://www.nennstiel-ruprecht.de/bullfly/index.htm#Figures
 
Joe Woosman said:
Alaninga,

I assume your question relates to a wind from right to left on a right hand twist barrel seems to push the bullet higher on the target relative to no wind. This has to do with the gyroscopic forces of the spinning bullet. The nose of the bullet turns into the wind and upward creating lift. If you really want to know more about it here is a link to some great information on the subject. http://www.nennstiel-ruprecht.de/bullfly/index.htm#Figures
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I think it has more to do with gyroscopic precession. But I did read the link. The force ends up 90 degrees from where applied.
Bill
 
r44astro said:
I think it has more to do with gyroscopic precession. But I did read the link. The force ends up 90 degrees from where applied.
Bill
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I'm probably talking above my pay grade here but my understanding was gyroscopic precession explains the rotation of the bullet about its axis. The wind causes a high pressure on one side and a low pressure on the other.... Lift - right?
 
I am describing GP in simple terms, I do not know the math involved. The only reason I remember anything about is I am CFI Rotor Wing. So I am suppose to know how teach the physics involved in helicopter flying and the rotor is a gyroscope. I do not think the original idea of this thread was about this action on bullet. I may be wrong, but where ever the axis of bore is when bullet leaves the bullet does two things for sure, slows down and drops toward center of earth below the bore line. Unless of course the bullet has lift but I do not think that is the case. But heck I have been wrong three times this morning already!
Bill
 
r44astro said:
I am describing GP in simple terms, I do not know the math involved. The only reason I remember anything about is I am CFI Rotor Wing. So I am suppose to know how teach the physics involved in helicopter flying and the rotor is a gyroscope. I do not think the original idea of this thread was about this action on bullet. I may be wrong, but where ever the axis of bore is when bullet leaves the bullet does two things for sure, slows down and drops toward center of earth below the bore line. Unless of course the bullet has lift but I do not think that is the case. But heck I have been wrong three times this morning already!
Bill
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I'm not using the term lift as in only up or down as though it had wings but in any off axis movement caused by pressure differentials. http://www.nennstiel-ruprecht.de/bullfly/fig9.htm

And then there is this, which in theory could cause the bullet to go above the bore centerline.... http://www.nennstiel-ruprecht.de/bullfly/fig13.htm
 
FBecigneul said:
I just don't see the bullet ever being above the axis of the bore. When I touch one off in a bench rest scenario, the rifle comes back and the butt goes down and therefore the muzzle goes up. That would put the axis of the bore above the point at which it was at the moment before ignition. As was pointed out earlier, the axis of the bore is above the line of sight of a rifle scope and more so in a long range rifle that may have a rail with 10-20-30 or more MOA minute of angle built into it.
If I stepped on toes................
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FB - Just for the sake of discussion, if you had more mass above the bore centerline like a heavier scope than the sock, the muzzle should drop and the butt rise. (Free recoil).
 
Alaninga said:
I know for all 'practical' physics that a bullet drops below a bore's axis as soon as it leaves the barrel. IF a wind [strong?] is coming from the right, and the bullet is spun in a right handed twist bore, will it rise above the bore's axis a small amount? Or will the right crosswind's effect only 'slow' it's fall compared to a 'no wind' shot?
: )
Really, probably discussed a million times, but I wasn't listening :)
Click to expand...

Theoretically, yes. Practically, no. The lift from a right wind is less than from an upward wind, and it takes tornado force upward winds to lift a bullet in opposition of gravity. Think about the terminal velocity of a bullet dropped from a plane. To lift the same bullet, the upward wind would have to be greater than that. The terminal velocity of a person is less (lower sectional density;)), so in a wind strong enough to blow a bullet upward, you would be blown off the bench.:eek:
 
With all the things going when a bullet is fired, recoil, wind, gyroscopic action / precession, bag hardness, mirage and so on, it is a miracle I hit the paper!
 
It's called gyroscopic drift or spin drift. The bullet weather vanes slightly in the direction of the twist. It can be calculated but only comes into play at longer distances when first round hits are important. Read one of Bryan Litz's books for a detailed mind numbing explanation.
 
Alaninga said:
I know for all 'practical' physics that a bullet drops below a bore's axis as soon as it leaves the barrel. IF a wind [strong?] is coming from the right, and the bullet is spun in a right handed twist bore, will it rise above the bore's axis a small amount? Or will the right crosswind's effect only 'slow' it's fall compared to a 'no wind' shot?
: )
Really, probably discussed a million times, but I wasn't listening :)
Click to expand...

My understanding is that there is no connection between gravity and and bullet velocity. As an example if you could drop a bullet out of your fingers at precisley the same time another bullet left the muzzle, regardless of velocity, providing the bore was perfectly parallel with a huge surface plate both bullets would hit the surface plate at the same time. If that is correct than it would stand to reason that regardless of cross wind direction even though one direction would be higher or lower they would both be LOWER in relation to the bore. Sounds logical to me.
 
Gravity is unaffected by velocity. You can not tell the difference between gravity, acceleration and deceleration. There are gyroscopic forces on the bullet because it is a gyroscope. If it was not (figure it out for yourself) it would move greater distances in a cross wind just like an airplane (vector analysis) I am sure there are at least a lot of private pilots out there, -get your Jepperson Circular Computer out.. In a right hand twist barrel, if the wind is a perfect cross wind from the right, the bullet will move up and left. Up because the force applied to the right side of the bullet is realized 90 degrees in the direction of rotation which would be the bottom of the bullet ((Gyroscopic Precession) (not sure what percentage of drop this can overcome)) the left movement is because the bullet is flying in a mass of air that is moving right to left. The opposite is true for left cross wind. The opposite is true of a left twist. I do not know if a bullet could ever move up more than gravity moves it to the earth, I doubt that. Remember Trout's Law of Gravity.
Proof that the Earth Sucks!
The Trout
 
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