My friends, Kathy

[Vibe]

My friends:

Thank you for your fine responses.......

It is impossible for a flush mounted muzzle device to stop the muzzle, no matter how heavy, or light, it is.

In truth, even then the muzzle is not "stopped", except in particular higher harmonics. There are any number of non-interfering methods that would prove this, laser displacement devices, etc.
http://www.keyence.com/products/vision/laser/lt9000/lt9000.php
http://www.keyence.com/products/vision/laser/lkg/lkg.php

However you forget about reflected wave behaviour. The tuner I referenced is a reverse cantilever, that while mounted flush with the muzzle, actually holds the weight several inches away from the muzzle - back toward the action. And in the case of the one used to make the Mini-14 accurate, almost all the way back at the action, forcing the reflecting node to be at the muzzle.

 

[Jetmugg]

Definitions

I think this discussion needs some clear definitions that everyone can understand precisely. We need a common language and understanding.

Someone please define "stop"

Someone please define "node"

Someone please define "parallel node"

If everyone can agree on these definitions, the ensuing discussion will be much easier to conduct and will make more sense.

SteveM.

 

[Vibe]

I think this discussion needs some clear definitions that everyone can understand precisely. We need a common language and understanding.

Precisely what has been asked for from the beginning.

Someone please define "stop"

Stop - to hold motionless (even if instantaneously - so long as the bullet exits in that instant)

Someone please define "node"

Node - typically the crossing point in a standing wave pattern, the point of least transverse motion (but maximum angular motion).

Someone please define "parallel node"

No such animal in physics to my knowledge.

If everyone can agree on these definitions, the ensuing discussion will be much easier to conduct and will make more sense.

SteveM.

Like I said. We've all asked for this before, to no avail.

 

[Wilbur]

The one that bothers me

I don't have the experience with rimfire to be posting in this thread but I have seen quite a bit of centerfire stuff. Every now and then, we screw on a barrel that shoots whatever you stick in it. This powder charge, that powder charge, this bullet, that bullet....with no tuner at all. This barrel seems to fit the "muzzle stopped" characteristic but if not, it's what we're looking for anyway.

My questions are, how can this occur with no tuner at all and how can it ever occur if the magic can't be at the end of the barrel?

 

[Vibe]

My questions are, how can this occur with no tuner at all and how can it ever occur if the magic can't be at the end of the barrel?

I have a partial theory on that one Wilbur. That the proverbial "hummer" barrel is in fact "defective" in a quite specific manner. The bore is not quite straight - EXCEPT when under the influence of gravity hanging off of a receiver. This would remove the whip that results in a "normal" or "perfect" barrel that is sagging slightly due to gravity when the high pressure pulse tries to "straighten" the curve out. The barrel that is prestraightened (as it were) is not thrown around in the same manner. But like I said, it's just a theory. But it does fit the facts in a couple of key areas - it explains in part why "hummers" are so rare. (We've been looking for a more perfect barrel as opposed to a slightly less than perfect one) And it fits the logic of the exercise.

 

[Wilbur]

That brings up another question

If gravity/barrel droop is the deal then why not use a full length stock and support the barrel such that it doesn't have any droop?

 

[Butch Lambert]

What effect does Shelley's opposed rare earth magnets have at the muzzle?
Butch

 

[Vibe]

If gravity/barrel droop is the deal then why not use a full length stock and support the barrel such that it doesn't have any droop?

Barrel diameter grows with the addition of high pressure - the barrel would "bounce" out of the stock. (Talking very small motions here, but important ones.) Same reasons a less than full floated barrel will often behave erratically - the "bounces" aren't consistent.

 

[HuskerP7M8]

I have a partial theory on that one Wilbur. That the proverbial "hummer" barrel is in fact "defective" in a quite specific manner. The bore is not quite straight - EXCEPT when under the influence of gravity hanging off of a receiver. This would remove the whip that results in a "normal" or "perfect" barrel that is sagging slightly due to gravity when the high pressure pulse tries to "straighten" the curve out. The barrel that is prestraightened (as it were) is not thrown around in the same manner. But like I said, it's just a theory. But it does fit the facts in a couple of key areas - it explains in part why "hummers" are so rare. (We've been looking for a more perfect barrel as opposed to a slightly less than perfect one) And it fits the logic of the exercise.

Vibe

There’s logic in your post, but aren’t straight barrels rather rare? The evidence I’ve seen suggests that crooked bores are the norm no matter who produces them.

And if you’re theory is correct, would it not validate barrel indexing?

The testing done by Mike Ross both before and after his article in “Precision Shooting” has firmly convinced me that barrel indexing works and is repeatable.

Of course, this only deals with rimfire, so I don’t know if it’s also valid for centerfire

 

[Vibe]

Vibe

There’s logic in your post, but aren’t straight barrels rather rare? The evidence I’ve seen suggests that crooked bores are the norm no matter who produces them.

I agree, perfect barrels are extremely rare, almost as much as the ones "defective" in only the precise specific way to cause a "hummer"

And if you’re theory is correct, would it not validate barrel indexing?

Yes, I suppose it would. A good barrel, and even a great, almost perfect, barrel might not show any difference when indexed to different positions. But if (and I will grant that it's a huge if) my hummer theory is correct, indexing a hummer barrel would throw it out of tune.

The testing done by Mike Ross both before and after his article in “Precision Shooting” has firmly convinced me that barrel indexing works and is repeatable.

Since as you say, most barrels are not perfectly straight, this makes sense.

Of course, this only deals with rimfire, so I don’t know if it’s also valid for centerfire

Rimfire has it own separate set of gremlins in addition to the barrel issues.

But like I stated before. all this is simply theory. I really have no way to empirically prove or disprove any of it. We do use the laser displacement guages I mentioned in my post to Bill where I work, but no one is going to allow me to borrow one for a weekend at the range.

 

[gordon gauge]

Barrel diameter grows with the addition of high pressure -

Well, if overtightening a muzzle tuner can decrease bore diameter, the pressure from a .22rf could certainly increase diameter.

Good thing it is happening behind the bullet......

 

[Bill Myers]

Butch,A little story on magnets as a tuner influence,My Rail Gun has a setup that uses 6 rare Earth Magnets,They can be positioned any where on the barrel,all the way back to the action,And they can be put at different positions around the barrel,One side or even around all sides,I did Quite a lot of testing with them & strange things would happen,On a dry day ,The first patch would come out with condensation on it,I always dry patch to see what is going on when testing,Take the magnets off,no more moisture in the bore,I could change the Harmonics by moving the magnetic field forward or aft on the barrel,but they never really worked as well as a adjustable tuner when it was tuned.I could meassure the actual barrel movement on the barrel & i have NEVER found a dead spot anywhere on the barrel,There are areas that move less than others ,but the muzzle always has a slight movement in the 7 to 2 oclock position.My hold indicators can measure in 2 directions at the same time & the barrel always moves more up than down,I think that is is influenced by the bedding in a stock,but this a theory,yet to be proved.Not all barrel shoot their best when the muzzle has less movement,One thing that i have found to be repeatable,The barrel must be tuned to itself,not the ammo.Think about this,You take a 8" dia peice of steel & make a barrel out of it,Its not going to vibrate much,But you still need to find a ammo or bullet Powrer combo that it will favor,Tuners make the barrel believe that they are 8" in Dia,But they still need the rught stuff put down them. BILL

 

[tim]

Bill, might I inquire as to what you believe the reason is for the magnet-moisture observation?

 

[Bill Myers]

Tim,I do not have the slightest idea why,,Someone other than myself will need to explain the whys.One of the good points of the magnets is that most of the different lots of ammo will impact in the exact same place,whereas with a tuner,they will wander around,but shoot tighter groups. BILL

 

[Vibe]

I knew that the dipole moment of the water molecule was affected by a magnetic field (you can bend a thin stream of water with a magnet to see this) - might explain the condensation in the field area.
Somehow I had envisioned using the magnets to support the weight of the barrel, without actually contacting the barrel, to relieve the cantilever sag and straighten the bore.

 

[Jetmugg]

How about some research?

It sounds like what is needed here is some university-level graduate student research. (and related measuring equipment). Attach strain gages to different spots on the barrel, and actually measure the deflection in the barrel under various conditions Use some high-speed camera techniques to define the movement of the barrel and test systems for "stopping" the muzzle. Once some basic data is collected, a computer model can be created to test various barrel designs, material compositions, "muzzle devices" and the like. It would be fairly straightforward work for someone in a mechanical engineering or materials engineering/metallurgy program.

Perhaps the elusive "parallel node" could be located.

The big question is - who wants to fund this kind of research?

SteveM.

 

[Bill Myers]

Vibe,The Magnets do not touch the barrel,I made a fixture to hold the magnets .030 from the barrel.All the way around,& i could take any or all the magnets off,but they needed to opposite each other as to hold the barrel in the field. I might get the seup out & test it some more,Right now ,I have a glued on barrel block system on the rail & a Harrells tuner,I have been testing a Barrel for Benchmark BILL

 

[Vibe]

It sounds like what is needed here is some university-level graduate student research. (and related measuring equipment). Attach strain gages to different spots on the barrel, and actually measure the deflection in the barrel under various conditions Use some high-speed camera techniques to define the movement of the barrel and test systems for "stopping" the muzzle. Once some basic data is collected, a computer model can be created to test various barrel designs, material compositions, "muzzle devices" and the like. It would be fairly straightforward work for someone in a mechanical engineering or materials engineering/metallurgy program.

Perhaps the elusive "parallel node" could be located.

The big question is - who wants to fund this kind of research?

SteveM.

Steve. As I alluded to earlier, it's been done. That is precisely what those folks at Lost River Tech did. (I think I remember the name right). And they generated a fairly extensive thesis on the subject. From this they developed a tuner of sorts and offered it and the results of the thesis for sale, as well as the program used in making use of the data. This was several years ago, and I'm not sure many references to the tests even exist on the net any longer.

But strain guages, like many other devices that physically attach to the barrel, very likely alter the same phenomenon that one is trying to measure. Which is why I suggested the purely non contact techniques.

 

[Vibe]

Vibe,The Magnets do not touch the barrel,I made a fixture to hold the magnets .030 from the barrel.All the way around,& i could take any or all the magnets off,but they needed to opposite each other as to hold the barrel in the field. I might get the seup out & test it some more,Right now ,I have a glued on barrel block system on the rail & a Harrells tuner,I have been testing a Barrel for Benchmark BILL

Only problem I can imagine with a magnetic field set up would have to do with the drastic nonlinearity of the forces involved. I'd have to look it up again but it seems that both the attractive and repulsive magnetic forces vary as the cube (or to the 4th power) of the distances involved. So very small motions could set up some very large inconsistencies. I'd be real interested in seeing the results you found.

 

[Jetmugg]

Good Point

Vibe:
Good point about using non-contact techniques to measure the movment. I happen to be a metallurgical engineer, and these kinds of technical issues are of particular interest to me.

SteveM.