Barrel harmonics

[D Sanders]

Hello all,
This may sound like a dumb question for us ml'ers since some of those unmentionable guns have those fancy adjustable gizmos on the muzzles to control harmonics. Has anyone tried to experiment with the way a muzzleloading barrel fits in the stock? Would it be to a shooters advantage to glass bed a stock or try to adjust wedge pin fit etc. It may not make any difference since most ml barrels contact the stock at least half or all the way up. That eliminates a free floating barrel. We all seem to consentrate on powder charges, patch and lube combinations. I would think long muzzleloading barrel has to have a certain amount of vibration to it. Has anyone tried anything to control this situation?

H H 60

 

[coloradoclyde]

You can't compare an apple to a watermelon and then expect the watermelon to make good pie.


First you need to understand harmonics before you start applying remedies.

For the most part, barrel tuners are a gimmick...and when they do work they solve an existing problem....usually it's a self imposed problem...and when it's not there are other ways to correct the issue.

Long barreled muzzleloaders already have vibration control....it's called pins, long stock and nose cap.

 

[azmntman]

I have but limited experience with glass bedding and less than zero understanding of a vibrating barrel (other than a miss on a 8x8 bull elk with a stout pine tree nearby). I had a badly cracked stock (tried to pound a wedge in when barrel not seated well). My gunsmith pal fixed the stock so's ya have to look hard to see the damage and glass bedded it. It is a .58 cabelas hawkin. Groups shrank in half with the bedding? YMMV

 

[old gunsmith]

I've always looked at it this way: in a modern gun the stock supports the barrel; in an antique style, the barrel supports the wood. old gunsmith

 

[coloradoclyde]

I have but limited experience with glass bedding and less than zero understanding of a vibrating barrel (other than a miss on a 8x8 bull elk with a stout pine tree nearby). I had a badly cracked stock (tried to pound a wedge in when barrel not seated well). My gunsmith pal fixed the stock so's ya have to look hard to see the damage and glass bedded it. It is a .58 cabelas hawkin. Groups shrank in half with the bedding? YMMV

Don't think of "bedding" as a way to cut your groups in half....What bedding did was correct an existing problem so that your gun could shoot normally.
Bedding a gun without a problem will not necessarily make it shoot better....and could easily make it shoot worse.

 

[bender20]

Clyde is correct a well made gun either modern or antique doesn't need to be bedded or free floating. They are just ways to fix a problem they are not the correct way to build a gun.

 

[azmntman]

I'm not knowledgeable enough to argue or agree. 90% of my guns are BP and shoot em 95% of the time. Just posted it worked for me (once?) Nope, I didn't beg him to bed any others...just a note that it worked for me?

So what kinda issue you think it might have helped alleviate? Maybe the wedge was off or something? It shot pretty well to begin with or I wouldn't have kept it but sure did shoot better after?

 

[Loyalist Dave]

Well the only time I've seen even modern-rifle shooters worry about "harmonics" was at very far ranges. I'm talking at 500+ yards distance.

IF you're not shooting out past 500 yards, I'd not worry about harmonics at all. If you were, you'd need to be shooting either at a high, match level, OR shooting an enemy for it to be a factor.

I must confess, however, of reading a recent Muzzleloader magazine article about a wrought iron barrel, and the fact that wrought iron is a "dead" metal, hence no harmonics, or very little. So what I was wondering was if a gunsmith was to mill an insert for a wrought iron blank, to build a "sheathed", 1000 yard, (modern ammunition) match rifle barrel with the wrought iron, would that give the shooter any advantage? Sort of applying the very old to the new....,
:idunno:

But for traditional muzzle loading rifles, I'd say it's not a concern for the vast majority of us.

LD

 

[hanshi]

I never give it a thought. All the barrels I've shot hummed in glad harmony already. :v:

 

[necchi]

some of those unmentionable guns have those fancy adjustable gizmos on the muzzles to control harmonics.

Barrel harmonics is an issue for modern centerfire guns but usually only for handloaders and as it applies to finding a point of "harmonic balance" allowing the projectile to leave the barrel at the same time each time in the sequence of any present occurring harmonic vibration.
(it's all an involved and different conversation)
But with the heavy walled barrels of ML, generally lower velocities and with round or heavier projectiles we use, any minor actual barrel movement within itself as harmonics refers to is so minimal as to not be of concern.

Has anyone tried to experiment with the way a muzzleloading barrel fits in the stock?

The biggest area of fit concern with Ml's is the rear of the barrel and tang area and the first few inches forward of that point,, only because this area takes the brunt of the recoil and can (with poor fitting) be the spot where a barrel might shift in the stock,, but that's not "barrel harmonics" it's a physical change of position. Even tiny changes there will upset all the following shot placements.
Many factory guns can and do benefit from bedding to get a good fit in that area.

We all seem to consentrate on powder charges, patch and lube combinations.

Yup, and we should be,, just like accuracy in modern guns,, Ml's need consistent conditions each time for repetitive shot placement and all of that has to do with the load, how's it's loaded and handling of the rifle during the shot.

 

[Zonie]

I think when it comes to Traditional Muzzleloading Rifles, harmonics don't play much of a part in the guns accuracy.

Modern cartridge guns have skinny, fairly thin barrels that don't have a lot of mass (weight) to them so they can be made to vibrate fairly easily.
Compared with the barrel, these CF guns have stiff stocks so the stock can give some support to the barrel.

Most muzzleloader barrels are thick, heavy things that don't vibrate easily and when they do, the magnitude of their movement is very slight.
Muzzleloaders stocks are rather weak compared with the strength of the barrels. So much so that the barrel tells the stock where it is going to be.

This leads me to think that bedding a muzzleloaders barrel is a waste of time if vibration is the thing that one is trying to eliminate or control.

I will admit that a muzzleloading barrel does need to fit the stock closely though.

If it is too loose, the barrel can move around during the shot and this can change the point of aim before the ball/bullet has left it.

 

[azmntman]

I will admit that a muzzleloading barrel does need to fit the stock closely though.

If it is too loose, the barrel can move around during the shot and this can change the point of aim before the ball/bullet has left it.
Just Jim...
:hmm:
Maybe thats what bedding corected im my split stock .58 :idunno: All I know is it shoot better now by far. I think he did the bedding to strengthen the repair (was a bad bad ugly break....I actually took it to him to see what he would charge to duplicate a new stock)

 

[Vaino]

Prior to shooting MLers I was into handloading for CFs for the best accuracy obtainable w/ a particular rifle.

Upon ignition a harmonic is produced that vibrates the bbl like a pendulum and the most accurate loads are those that time the bullet exiting from the bbl at a point of the pendulum swing that is at either end of the pendulum swing where the bbl "stands still"....in other words the bbl reaches the end of it's travel and stops and then starts its travel to the other end of the swing. The exiting bullet "sees" a non-moving bbl.

A MLer because of the low pressures produced by BP and the heavy weight of MLing bbls, doesn't produce harmonics to a degree that greatly affects accuracy. CF rifles have light weight bbls that one could call "whippy".

When I first got into MLing, I was amazed at how easy it was to obtain accurate loads if one used quality RBs and suitable patches......the patches are probably the most important component in obtaining excellent accuracy.

The harmonic adjusters found at the end of a few CF bbls do work and are mainly for factory loads in lieu of developed handloads that have the bullet exiting at either end of the pendulum swing and aren't needed for MLers...and besides they don't look good.....Fred

 

[Kansas Jake]

Harmonics is interesting. Not a ML, but observation of a rimfire target rifle a couple of weeks ago. I was serving as RSO at the local range and one of the regulars was practicing with a free floated bench 22. I could actually see the vibration of the barrel when he shot the rifle. It surprised me that I could see the movement on a 22 with a heavy barrel while the stock stayed still. He said it is all about consistency of the vibration when trying to put the little bullet in the same place at 100 meters.

Unless is shooting a bench rest muzzleloader bedding or free floating a muzzleloader probably won't make muck difference.

 

[Artificer]

Interior and Exterior ballistics was just beginning to be understood in the early 18th century.

While they did not understand wave theory and the science of barrel harmonics, they understood what worked best on building the rifles that wound up giving them better barrel harmonics.

One of the worst things that can happen with a barrel is when there is a negative node of vibration caused by something affecting the barrel along the barrel's length. The more it keeps the barrel from vibrating smoothly as possible, the worst effect it will have on harmonics.

It has already been mentioned barrels were made of dead soft iron until the early 19th century and iron vibrates more uniformly than steel, when the steel alloy is not uniform throughout it's thickness.

They knew the breech end needed to be inletted tightly, but what they did going further forward in the barrel channel is interesting when we apply the science of barrel harmonics.

They inletted the sides of the barrels fairly closely so as not to allow water, mud, etc. inside the barrel channel. However, the bottom three flats of the barrel channels were often not tightly inletted a little forward of the breech until very near the muzzle. Matter of fact, it has been reported that many 18th century rifles had round bottom or loose inletting between the breech and muzzle. They did it that way to speed up making the rifle, but it also did not introduce negative nodes of vibration when the inletting was loose, because the wood fit to the barrel was loose.

Next point is they usually filed the holes for the barrel pins so it allowed movement forward and backward as the stock swelled and shrank. IOW, only the bottom of the barrel lug holes kept the barrel from being loose up and down. What that did was minimize the negative node of vibration at each barrel lug, though the primary purpose of doing it was to keep the stock from cracking.

They rather tightly inletted around the muzzle of the barrel to keep water/mud/foreign matter out of the stock (also to make it look good) but it did not put much pressure on the barrel at the muzzle, which would have caused a bad negative node of vibration at the muzzle.

All things considering, the forearm put very little pressure on the barrel, so it did not set up bad negative nodes of pressure vibration on the barrel.

There was a lot more experimenting done in the 19th century on barrel shapes and stocks that also helped barrel vibration, even though they did not fully understand it helped barrel vibration/harmonics.

Gus

 

[Artificer]

Sorry, I guess I should really explain negative nodes of vibration.

The easiest way I have found folks can visualize it is if they have been on or by a dock when a boat goes past. The boat moving through the calm water causes pretty smoothly uniform waves to emanate out from the boat.

Now, when those waves hit the dock posts going down into the water, you will see the post cause the waves to be broken and actually there is some little waves going back from the post towards the boat. The faster the boat travels, the more force the waves hit the dock post and the more backward wave action as the waves bounce back from the dock post. The backward waves caused by the dock posts are very similar to the negative nodes of vibration in a barrel.

Hope this is a little clearer than mud.

Gus

 

[George]

Interior and Exterior ballistics was just beginning to be understood in the early 18th century.

I decided early on in my BP shooting experience that barrel harmonics probably weren't a big problem with muzzleloaders, but have always found this passage from Wm. Cleator in 1789 to be very interesting.

"Pieces intended for shooting with ball, whether they be plain or rifled, ought to be of much more equal thickness from the breech to the muzzle, than those that are intended for shot, only. In every barrel, there is an undulating vibration communicated to the metal by the explosion. This is most remarkable in a thin barrel, and when the charge is great; and may be rendered very evident by the following easy experiment.

"Take a piece of fine steel or iron wire, that is tempered so as not to stretch readily; pass it once around the thin part of a barrel, and twist it tight. The piece being then charged and fired, the wire will be found burst asunder, or considerably untwisted. It is evident, that such a degree of vibration in the barrel, must have an effect upon the ball in its passage through it; and that the only means of preventing it, is, by having an additional quantity of metal in the barrel. and especially in the fore part of it. The same circumstance certainly obtains, though in a much less degree, in fowling pieces; and on this account, as well as on that of the recoil, a barrel which is strong enough to withstand any charge that is required, may yet have too small a quantity of metal in it."

I've always hoped someone would run this experiment for us. Gus? :grin:

Spence

 

[Artificer]

Spence,

Glad you chimed in on William Cleator's work.

Folks,

This gives me a chance to publicly thank Spence for introducing me to that work in the last year or two. I was going to use some info from Cleator's works to show just how close they came to modern ballistic theory in the 18th century, but I could not find where I saved the link to it and could not find it quickly on the web. :redface: :haha:


In Cleator's work, he talked about a "permanent elastic fluid," which Spence had correctly identified as the propellant gas from the burning powder. Recently I found what I believe is the source of that and some other information in Cleator's work. It may or probably came from "The New Principles Of Gunnery," by Benjamin Robins and published in 1742.

http://arc.id.au/RobinsOnBallistics.html

Here in more info on Robins and another early Ballistics pioneer, Euler.
http://www.academia.edu/5891602/Th...of_Robins_and_Euler_in_the_eighteenth-century

More later.

Gus

 

[Artificer]

P.S. One more great link:
http://www.sciencedirect.com/science/article/pii/0734743X9290486D

Gus

 

[George]

Gus, another early writer about ballistics is Thomas Page, in his "The Art of Shooting Flying:" He built and used a version of the ballistic pendulum, did a lot of patterning experiments and wrote extensively on various aspects of ballistics, very math oriented and complex. He delves into factors I have never seen written about before, many of which I find pretty dense. His ideas aren't always well aligned with our modern ideas, but are fascinating to read, nevertheless, and give a nice glimpse into the 'modern' thinking about ballistics in the 1760s.
https://books.google.com/books?id=...UAhVE0oMKHc1BDPAQ6AEIQTAG#v=onepage&q&f=false

Spence