Stopping the muzzle, part 3, Calfee

K

Kathy

Guest
My dear centerfire friends:

The "exact center" of the "parallel node", in the vibration pattern of a rifle barrel, neither advances toward the crown, nor, retreats away from the crown, as bullets are fired at different velocities through the bore.

Your friend, Bill Calfee
 
Bill, does this mean that bullets fired at different velocities produce the same vibration frequencies and barrel oscillations?
 
If you pluck a guitar string, the frequency that is produced is independent of how hard it is plucked. It would seem that coordinating bullet exit with muzzle position would only be important if the barrel is moving (in the sense that Bill defines motion for the solution of this sort of problem). Did I get that right? On the other hand, a low rifle weight limit, combined with more violent internal ballistics, recoil forces, and rifle balance and tracking issues would seem to complicate the problem in some applications.
 
burtona said:
Bill, does this mean that bullets fired at different velocities produce the same vibration frequencies and barrel oscillations?
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I think it means that the events that set up barrel vibration have a minimal effect on a properly tuned barrel, therefore, velocity (hence the moment in time that the bullet exits the muzzle) has little to do with point of impact.

-Dave-:)
 
Bill...

The "exact center" of the "parallel node", in the vibration pattern of a rifle barrel,

Can you define this ? I got in a lot of trouble when I made an assumption about your definition of "stopped", so I'm just trying to avoid that again. I realize you may have defined this in P. S. but maybe you could explain it again.
 
My centerfire friends

My centerfire friends:

I quote from myself: "The "exact center" of the "parallel node", in the vibration pattern of a rifle barrel, neither advances toward the crown, nor, retreats away from the crown, as bullets are fired at different velocities through the bore."

My friends, as the vibration frequencies increase, the parallel node becomes shorter in length. As the vibration frequencies decrease, the parallel node becomes longer in length..........BUT.....the "exact center" of the parallel node, never, varies in distance from the crown.

This law of physics is why we can use a tuner, of the correct weight and placement, at the muzzle, for the size of our barrel, which will move the "exact center" of the parallel node to the crown, stopping the muzzle.
When this is achieved, no further adjustment of the tuner is ever necessary.

Your friend, Bill Calfee
 
I don't understand, Bill. You have repeated what you said and I get this, but it's still not clear to me where on a sine wave that you think a "parallel" node exists. You talk about the "length" of a node, but nodes are points, they have no length. The point usually referred to as a node is not on the curve at a point that is parallel to the axis. The point on the curve referred to as an antinode is where the curve is parallel to the axis. Actually the curve is not parallel but a straight line tangent to the wave through the antinode would be parallel to the axis.

I am not trying to dispute anything you say - I'm just trying to understand WHAT you are saying. I think, I assume, I guess, based on what you have said before, that you want to release the bullet at a node, but then you say you want to release the bullet at a "parallel node", then you talk about changing the length of a node????? It's not your fault , I'm just having trouble getting it.
 
Pacecil

What happens to a sine wave if we increase its ampitude but not it's wavelength? Does it still intersect the plane at all the same points? How is it's dwell affected?
Lynn
 
Bill

Varmint Al asked this question in another thread:

"I just have one question. If the muzzle is completely stopped then wouldn't the 1075 fps bullets strike the target higher than the 1035 fps bullets?"

Tom D subsequently calculated that the POI difference, in a vacuum, would be .228" at 42 yds due to the difference in time of flight between the two bullets.

How large are the groups you achieve during your mixed ammo testing?

If your groups are significantly smaller than .228" at 42 yds, how do reconsile your results with Tom D's calculated results?

In your stopped muzzle situation, is there any variance to the departure angle of the bullet?

Asked another way, do bullets of varying exit the muzzle at the same x, y and z vector (I recognize that vector is ambiguous in this question, since the velocity of the bullets is not identical) for each shot? Put another way, is the crown of the muzzle in the same position in space, x, y, and z when the differing velocity bullets exit?

Enquiring minds want to know. Thank you.
 
Mike,

You are dead right, at least in my eyes ! If the barrel is tuned so that the muzzle is now not moving the velocity variations will still have an effect on the vertical. To get varying velocity ammo to impact at the same place the barrel has to be pointing in different places with each velocity. It is in fact tuned so that the slower bullet exits with a higher muzzle point.

The more of this stuff I read by the various guys that think they have it sorted the more I doubt that any of them actually know 100% what is happening.

Varmint Al's modelling whereby the whole rifle system flexes and moves and effects the barrel orientation makes the most sense to me. If a barrel vibrates then so does the action and the stock, maybe the tune in a fibreglass stock would be totally different if you moved the rifle to a wooden stock or moved that barrel from a Alloy action to a stainless, like a Panda to a Grizzly say.

In the meantime I am happy that my rifle shoots well over a range of conditions with an upper window N133 load and no tuner !!! :)

Bryce
 
BJS6 said:
Mike,

You are dead right, at least in my eyes ! If the barrel is tuned so that the muzzle is now not moving the velocity variations will still have an effect on the vertical. To get varying velocity ammo to impact at the same place the barrel has to be pointing in different places with each velocity. It is in fact tuned so that the slower bullet exits with a higher muzzle point.

The more of this stuff I read by the various guys that think they have it sorted the more I doubt that any of them actually know 100% what is happening.

Varmint Al's modelling whereby the whole rifle system flexes and moves and effects the barrel orientation makes the most sense to me. If a barrel vibrates then so does the action and the stock, maybe the tune in a fibreglass stock would be totally different if you moved the rifle to a wooden stock or moved that barrel from a Alloy action to a stainless, like a Panda to a Grizzly say.

In the meantime I am happy that my rifle shoots well over a range of conditions with an upper window N133 load and no tuner !!! :)

Bryce
Click to expand...

Its probably been nearly ten years ago now, maybe more, but I can recall Don Jackson out at the range repositioning his scope to obtain the maximum grouping potential of is rifle. That was the first time I'd ever seen someone take that approach, but it makes sense.

But, FWIW, I'm trying to keep an open mind. If Bill has answers to these questions, I'd love to hear them. There seem to be some folks on this board who want answer the questions for Bill. I believe they aren't 100% representing Bill's views and are speculating to some degree as to what Bill's answer would be, so I'm just trying to get the info from the horse's mouth. Maybe even an ole worn out lawyer like me can still learn 'sumtin.

Small ones.
 
BJS6 said:
If a barrel vibrates then so does the action and the stock, maybe the tune in a fibreglass stock would be totally different if you moved the rifle to a wooden stock or moved that barrel from a Alloy action to a stainless, like a Panda to a Grizzly say. Bryce
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I can say for sure that the barrel "rings" differently for me based on what the stock composition is. One tuner rifle that I shot at the end of last year was in a fiberglass Tooley/McMillan stock. Another rifle I put together recently is in a wooden stock very similar to the McMillan. When ringing the barrel on the wooden stocked rifle the ring was not nearly as clear as the one in the fiberglass stock. Maybe the wood absorbs some of the vibration. Anyway it was alot more difficult for me to discern where the dead spot was on this rifle. I have not shot it yet so I don't know if I got it correct or not.

I am wondering if there is a way to electronically measure the ringing so if the human ear isn't so good you could more easily find the dead spot.
 
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J,I ,Like you was not able to clearly hear the barrel tones when useing a wooden stock,No problem on the Composites,But i talked with Joe Friedrich & he advised me on a better grade Stethascope that has 3 different setting,one for Low.Medium & high pitch tones,They are expensive,BUt i now can hear even the smallest tones,I put one of my Bench Rifles into my Tool Fixture & checked it & found the so called Dead spot & then i used The Stethascope to verify the Results.I built myself a 6 Dasher & I wanted to use a Brake,So i left the Barrel Long,32" &Started adding weight to the barrel until the end was at the lowest tone,I Then made a brake of the same weight & put it onto the Barrel,It is 29 " ,that is where it ended up to get the muzzle Dead.I took the rifle up To Bruce Baers shop & he & I shot it from his indoor range,He has a sound proof room on the back of his shop & 2 windows slide open as so you can shoot out to 400yds .New Barrel First load,#2 Re15 & 105 Bergers .020 into the lands.At 100 yds it shot into the high ones & low Twos with Bruce & myself shooting it & it was tuned in my shop with a Stethascope,I have since shot it at 200yds & it is still in the 3's.I will now wait for the weather to get warmer & see if it will repeat,if so i can use a brake as a Non adjustable tuner. BILL
 
BountyHunter

Herman if you want it done Calfee style ring it off of the action.It gives you the added benefit of getting the tuners weight very close as well.I hired a Piano tuner to do it for myself as I wasn't getting it figured out too well.The piano tune did it in 5 mintes time and repeated it 3 times for me.He charged me one trip to the range for his services.
The 22 rimfire guys are ringing them as described above and if you visit there forum they give the details.
Lynn
 
To Lynn....

What happens to a sine wave if we increase its amplitude but not it's wavelength? Does it still intersect the plane at all the same points? How is it's dwell affected?
Lynn

Nothing will happen- the amplitude will increase and the wavelength will stay same because that is just what you said is done to it Yes, it will intersect the "plane" (I assume you mean axis) at the same points, because that is exactly what you have said you did to it I don't know what the "dwell" is.

I don't understand why you ask these questions, but I'll assume you consider the barrel as it vibrates takes on the shape of a sine wave - it does, if it is in a NATURAL vibration mode but I don't know what shape it has while it's in the FORCED mode. It's interesting to talk about the barrel vibrating this way but it has very little to do with our main concern here, and that is how the barrel is acting before the bullet leaves and what the tuner does during this time. It might be that the barrel DOES have the shape of a sine wave before the bullet leaves but I don't think any body knows this for sure. One thing is for sure, Calfee doesn't think it has a sine wave shape.
 
Pacecil

If you go back and read Bill Calfee's original post he says the parallel node never moves with velocity.In your post above you mention that if the wavelength stays the same it will intersect the axis at the same points.I am guessing Bill Calfee with all of his years of experimenting is saying the forced mode doesn't change the frequency of the barrel.It may change its ampitude but not its wavelength.
Does that make sense?

Now if the amplitude is increased alot we still have the same point on the axis as our critical point but on either side of it the shape rolls off very quickly.The barrel doesn't dwell or stay within a certain range on a high amplitude curve like it does on a low amplitude curve.
Does that make any sense?

Super impose a low ampitude wave onto a high amplitude wave to picture what I am saying.
Lynn
 
pacecil said:
What happens to a sine wave if we increase its amplitude but not it's wavelength? Does it still intersect the plane at all the same points? How is it's dwell affected?
Lynn

Nothing will happen- the amplitude will increase and the wavelength will stay same because that is just what you said is done to it Yes, it will intersect the "plane" (I assume you mean axis) at the same points, because that is exactly what you have said you did to it I don't know what the "dwell" is.

I don't understand why you ask these questions, but I'll assume you consider the barrel as it vibrates takes on the shape of a sine wave - it does, if it is in a NATURAL vibration mode but I don't know what shape it has while it's in the FORCED mode. It's interesting to talk about the barrel vibrating this way but it has very little to do with our main concern here, and that is how the barrel is acting before the bullet leaves and what the tuner does during this time. It might be that the barrel DOES have the shape of a sine wave before the bullet leaves but I don't think any body knows this for sure. One thing is for sure, Calfee doesn't think it has a sine wave shape.
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Well in the end everyone has their own opinions. Sometimes I have a hard time understanding Bill's way of describing things. But I have not doubt that he has the ability to build some of the most accurate RF rifles that one can buy. When you get to that point, I would say you have a right to lambast Bill..But ...until you get to that point....................Donald
 
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