Stopping the muzzle, part 2, Calfee

K

Kathy

Guest
My centerfire friends:

Any weight attached to the muzzle of a rifle barrel will slow down muzzle oscillations.

Your friend, Bill Calfee
 
Yep, I also agree, that's a true statement Bill! And anyone that says other wise is itching for a fight! I, and I believe, Varmint Al, would back you up on that 100%.
 
Dampen the amplitude of the oscillations - yes!
What does slow the muzzle oscillations mean? Does the frequency change or stay the same when you add weights to dampen the amplitude??
My physics courses were a long time ago but it seems I remember there were always more than one component of the equation to deal with.
 
Question Bill - -

Are you saying that the atmosphere has no effect on the tune of the rifle?

Thanks,

Pete
 
I talked to bill about this a couple of years ago and then I spoke with a person who deals in harmonics and he agreed completely with what bill said. Bill may not explain the exact terms properly but it's still easily understandable. One qustion I have for some....why does a tuning fork not need tuning in different atmospheric conditions? Once it is set, it stays that way and that is why if a tuned barrel is right, it does not need adjusting. It is also why with Bills method (the most effective method) the weight has to be past the end of the muzzle. Both before and past the crown (the tuner) will oscillate but the point at the crown will be a dead spot (as bill calls it, Stopped), thus different atmospheric conditions (to a point) will have no effect, just like a tuning fork. Kind of like the harmoic spots on a guitar, why don't they ever change place, even in different atomspheric conditions?

However, there is a lot more to rifle accuracy, even if you remove the wind, than barrel vibrations. Which is why a gun is a system and the barrel is a part of that system.

Many moons ago, back in my really youthful days in the army, I happened to catch a beer bottle in the back of the head. My ears rang pretty consistant for a few days.....so I have always considered myself in tune..:D:D

Hovis
 
HovisKM said:
I talked to bill about this a couple of years ago and then I spoke with a person who deals in harmonics and he agreed completely with what bill said. Bill may not explain the exact terms properly but it's still easily understandable. One qustion I have for some....why does a tuning fork not need tuning in different atmospheric conditions? Once it is set, it stays that way and that is why if a tuned barrel is right, it does not need adjusting. It is also why with Bills method (the most effective method) the weight has to be past the end of the muzzle. Both before and past the crown (the tuner) will oscillate but the point at the crown will be a dead spot (as bill calls it, Stopped), thus different atmospheric conditions (to a point) will have no effect, just like a tuning fork. Kind of like the harmoic spots on a guitar, why don't they ever change place, even in different atomspheric conditions?

However, there is a lot more to rifle accuracy, even if you remove the wind, than barrel vibrations. Which is why a gun is a system and the barrel is a part of that system.

Many moons ago, back in my really youthful days in the army, I happened to catch a beer bottle in the back of the head. My ears rang pretty consistant for a few days.....so I have always considered myself in tune..:D:D

Hovis
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Try this experiment in your spare time. Strike a tuning fork and then hold a propane torch or a lighter to it and see if heat makes it change tone.
 
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And these light contour barrels advocated for the heavy tuners heat up VERY quickly when shooting a 6PPC through them. Been there, tried that.
 
I don't know about applying that much extreme heat but I have used tuning forks between 20 and 100 degrees and there is no difference. Would you shoot a barrel that is to hot to touch? I sure wouldn't. It's just not even a remotely comparable experiment using a propane torch. What you would be doing is actually changing the actual structure of the steel (ie: hardness, and grain structure) of the tuning fork. It would never be the same again. A rifle barrel should never be shot so hot that it would actually have it's structure damaged. I have seen this done with machine guns and the barrel has to be replaced. Another words, so hot you could actually see the streak go down the white hot barrel. The temp of the barrel, as long as it is kept within reason, will not effect the barrel itself.

I had mentioned in a previous post on another thread about the army using frequencies to tune artillery barrels. But there is a round count per minute or hour they have to follow or you can get them to hot to permanantly change the pattern. The barrel can still be fired safely but you can't hit anything with it. The method is classified but sure wish we could see the data, cause I think they know for sure what is going on that we are all trying to figure out.

Hovis
 
It's just a high school physics experiment. We did it over a bunson burner holding the tuning fork in our hand. It wasn't heated hot enough to burn our fingers. Get a cheap tuning fork and try it for yourself with a cigar lighter then you will know. You will hear the tone change as it heats.
 
Interesting...was the frequency changing or just the tone key? Wish I had a scope available to see what is actually changing. Just wondering if the amplitude was changing or the freq. If it's just the amplitude, then no change to the actual effect of the node (pitch freq.) would be changing. I don't know if I'm sounding confusing or not but in simplier terms. There are many different pitches of the same notes in music. I could be explaining this wrong, been way to long (mid 80's) since I was involved with it.

Hovis
 
HovisKM said:
Interesting...was the frequency changing or just the tone key? Wish I had a scope available to see what is actually changing. Just wondering if the amplitude was changing or the freq. If it's just the amplitude, then no change to the actual effect of the node (pitch freq.) would be changing. I don't know if I'm sounding confusing or not but in simplier terms. There are many different pitches of the same notes in music. I could be explaining this wrong, been way to long (mid 80's) since I was involved with it.

Hovis
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Amplitude or frequency --- or both? I think probably both. Heat would make the metal expand slightly making the fork length a little longer changing frequency, and would probably cause the amplitude to increase also. But that's above my pay grade anymore and I'm not gonna drag out any old physiscs books. My high school and college physics classes go back to the late 50's and early 60's so I don't remember a lot of that stuff anymore.
 
The vibration characteristics of a tuning fork, or a barrel, will change as you increase the temperature. Not the air temperature but the temperature of the fork or barrel. This happens because the modulus of elasticity (stiffness) of steel drops off slightly as it gets hotter. Steel also gets slightly less dense (weighs less) as the temperature goes up. At normal temperature, you might subject a fork or barrel to, there would only be a very slight change. Whether or not you could detect or measure this will depend on how high the temperature and how sensitive your measuring instruments are.

Vibration starts in a barrel when you apply and quickly remove a force such as from a bullet or from the recoil force applied to the bolt face. Both frequency (how fast the barrel moves) and amplitude (how far the barrel moves) will change as you heat the barrel. If you vary how hard you "hit" (this is basically what the bullet does) the barrel, or you change the recoil force, then you change amplitude but not frequency.

Air temperature, or air density, changes might affect slightly how hard the bullet hits the barrel and thus can change amplitude. This is what is claimed to occur to a significant degree by Gene Beggs and some other posters.

All that Bill is claiming in this thread is that adding weight to the end of the barrel will affect how the barrel vibrates. I agree with this and note that the effect is to to both amplitude and frequency. What he thinks these changes look like at the time the bullet leaves the muzzle is something I'm still trying to get him to explain - or at least, explain so I can understand it.
 
pacecil said:
Vibration starts in a barrel when you apply and quickly remove a force such as from a bullet or from the recoil force applied to the bolt face. Both frequency (how fast the barrel moves) and amplitude (how far the barrel moves) will change as you heat the barrel. If you vary how hard you "hit" (this is basically what the bullet does) the barrel, or you change the recoil force, then you change amplitude but not frequency.

Air temperature, or air density, changes might affect slightly how hard the bullet hits the barrel and thus can change amplitude. This is what is claimed to occur to a significant degree by Gene Beggs and some other posters.
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Given that frequency and amplitude change with temperature does not support those that think a given tuner weight and position when "tuned" will stay "tuned" with temperature and velocity (ammo) changes it seem to me.
And that has been my experience in RF shooting since tuners first came on the scene.
 
OK...........this may or may not be on subject, BUT.......talk to ANYONE who's spent some time with the BOSS system and ask them if it stays in tune through weather/altitude/temp changes. I've messed with this style of tuner for 25yrs and invariably they fall apart for hunting just for the mentioned reason. You set them up at the range, they will literally make a steenking Browning A-bolt shoot factory rounds into 1/2"-3/4", then you walk away and they're spraying all over the landscape.


I have sold all of mine except for one 25-06 Win Classic which happens to have fine wood..........I've found the BOSS to be useless here in the West because I can dial in on my range (1085' above MSL) and drive an hour out to an elk hunt at 3500 or 5000ft and be off. If I go up into the high country I'm even further whacked. Not only does the tune go away but the POI changes even more than a bare barrel, IMO because the barrel THINKS it's heavier than it is....



al
 
Alinwa

I have heard this from alot of very serious shooters.
 
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