Barrel Harmonics

[Mike C]

Is anyone aware of any research to determine any difference in barrel harmonics between one of uniform cross section vs a swamped or tapered profile?
Mike C

[Hungry Horse]

I have not seen such a comparasent, but have had several old shooters say wrought iron barrels, and barrels that have a barrel liner soldered into them are better because of  better harmonics.

  Hungry Horse

[mark brier]

Wrought iron is dead iron

[Mike C]

I would guess the hardness or softness of the metal would be the most important variable, but does the profile also play a part?
Mike C

[mark brier]

It would take someone smarter than me with the appropriate equipment to measure such harmonics. But in my opinion all barrels have some form of harmonics. For example just the torque created with the ball/bullet traveling down  the barrel spinning with the rifling creates a circular harmonic. Reasons why some builders with completely bed the barrel channel with acraglass to ensure firm bedding of the barrel to eliminate hollow spots under the barrel. But a well made barrel will do better than I can shoot it anyway

[smylee grouch]

I'm wondering if stiffness has more to do with harmonics than weight. Could it be possible that where the barrel contacts the barrel rest might have some impact on that particular barrels harmonics? Would load combinations have an effect on harmonics? Maybe I wonder too much or is it curiosity?   

[Dennis Glazener]

Back in 1979 I attended a bench rest shooting seminar and Clyde Hart of Hart barrels was one of the speakers. Someone asked his opinion on a dead straight barrel versus one with a "bow" in it (many/most target barrels will have run-out mid-barrel but perfectly centered at breech and muzzle. Clyde said he didn't know the answer but he had a shooting family that if he sent a barrel with a dead straight bore, they would send it back. When Clyde was asked why they sent the straight ones back his reply was that they had some theory about consistent harmonics from the barrels with the bow and inconsistent harmonics with a dead straight barrel. Were they on to something, maybe, who knows but that family at the time held 4 or 5 world records!
Dennis

[Mike Brooks]

For off hand shooting I don't think harmonics between straight or swamped make a difference as you can't hold well enough to tell.. More important are things like lug spacing, pin instillation techniques, how well your barrel breech is set against the wood, etc. Even shooting off of a rest with open iron sights I think seeing your sights is a lot bigger deal than harmonics. If you slap a scope on there then harmonics may start to be a factor.

[Bob Roller]

Back in 1979 I attended a bench rest shooting seminar and Clyde Hart of Hart barrels was one of the speakers. Someone asked his opinion on a dead straight barrel versus one with a "bow" in it (many/most target barrels will have run-out mid-barrel but perfectly centered at breech and muzzle. Clyde said he didn't know the answer but he had a shooting family that if he sent a barrel with a dead straight bore, they would send it back. When Clyde was asked why they sent the straight ones back his reply was that they had some theory about consistent harmonics from the barrels with the bow and inconsistent harmonics with a dead straight barrel. Were they on to something, maybe, who knows but that family at the time held 4 or 5 world records!
Dennis

Did Mr.Hart say how MUCH bow was in the bore and can it be detected if the barrel was cut in half?? Can the bow be detected during cleaning with a tight patch. I have never heard of such a thing and I wonder if any of the barrel makers ever mention it. Bill Large didn't and I never heard Jim McLemore or Erie Stallman mention it. They both made high grade center fire barrels to MilSpec. This is VERRRRY interesting.

Bob Roller

[smylee grouch]

I'm wondering again, could a guy put a little bow in a perfectly straight barrel and get better harmonics?

[Gaeckle]

What Dennis is refering to are center fire barrels, at least I think he is. Clyde Hart made barrels for center fire rifles and his barrels were the thing to have on your bench rest rifle if you were competing in that sport venue. It's fascinating to watch one of these events and see the precision that goes into shooting bench guns. Everything is measured, wieghed, calculated and inspected with respects to what is being shot.

It's interesting that Clydes name is brought up, I used to hunt with Wally Hart in PA for many years, but haven't done so for the last ten or so years. Clyde would send barrels to Wally's bussiness and they would be used on the actions that Wally trued up and used. That combination of skills made for one heck of an acurate rifle.

But getting back to the general discussion......what does one mean by the term harmonics? Generally, harmonic refers to a signal or wave. Are we talking about barrel wip? Movement of the barrel, a swedging or compression effect, energy excerted from inside to the exterior of the barrel? Balance?

So often, I've heard this term bantied about, but not really well defined.

[Hungry Horse]

 i have heard this referred to a harmonic vibration. My suspicion is that the wrought iron barrels, and those with a soldered in liner, dampen this vibration, giving them  more consistent accuracy.

  Hungry Horse

[Darkhorse]

I define Harmonic Vibration as the pattern of movement in the barrel when the gun is fired. This begins upon ignition and when the bullet exits the muzzle it's flight path is affected. In a diagram it will resemble a sonic wave traveling down the barrel. I am not convinced this has much effect on a ML barrel as I've never recognized it.
In the centerfire world though I do deal with it. For instance I had a fine rifle in my gunsafe for about 15 years without seeing use. So one season I took it out to hunt with it and found the walnut stock had warped severly enough to wear bluing off the contact point on the barrel. I cut the warp out and glass bedded the entire rifle, did some trigger work, worked up some really concentric loads.
I shot several series of groups on a paper with 3 targets. Every 3 rounds I changed the seating depth. These were shot off a benchrest and with each change of seating depth the group itself would move on the paper. By changing the seating depth my POI changed because the bullet would exit at a different point in the vibration pattern. This knowledge allowed me to tune the load so every bullet exited at the same point so I could chase accuracy. This point is called a "Node" and there are more than one. Find one and your accuracy will suddenly improve. Sometimes drastically.
With this rifle the best it would shoot was around .750 with most loads a little larger. After all the work was done this rifle shoots under .250 with the smallest yet at .181." To obtain this size of grouping in a sporter barrel will require basic work on the rifle and much benchwork. But by chasing the Node almost any rifle can find improvement. But in a ML barrel I just can't see it.  Perhaps these barrels do produce Harmonic Vibration but I think it may be so small as to not be recognizable.
I agree with Mike Brooks concerning those items of important in accuracy. The pins and how they are fitted, a solid fit in the breech, are some things that must be done right for the rifle to show it's best accuracy.  I think a thick, heavy ML barrel will dampen most, or all, harmonic vibration.

[Dennis Glazener]

Did Mr.Hart say how MUCH bow was in the bore and can it be detected if the barrel was cut in half?? Can the bow be detected during
cleaning with a tight patch. I have never heard of such a thing and I wonder if any of the barrel makers ever mention it.

Yes those were precision benchrest rifle barrels.

Bob the way I saw those "bows", in several benchrest barrels, was when I set them up to chamber them. I had the barrel through the head stock and used hardened "spuds" inserted in the bore (muzzle and breech ends) and then used a dial indicator to have them with as close to .0001 run-out as I could get, this was both ends of the barrel running very close to dead true. You could then turn the lathe on and see the mid-bore wobbling. I have no idea how much run out there was in the middle but certainly enough to easily see it. Most of the these barrels were 20 to 26 inches long and made with the highest percussion machine available. I feel sure that the 38 to 48" barrel we use have as much "bow" as those benchrest barrels did.

I would suspect that the only way harmonic's would make much difference with ML barrels would be in some of the ML benchrest matches that are held.

Dennis

[Ky-Flinter]

Would load combinations have an effect on harmonics?

Absolutely.  When working up a muzzleloader load (or centerfire), we change one component at a time, until we find the smallest group/optimum load.  You are altering the barrel harmonics with each component change.

-Ron

[Jerry V Lape]

Here are some of the basics of harmonic vibration.  Shorter thicker barrels have smaller amplitude in their vibration verses longer thinner barrels.  Barrels free floated are more predictable in their vibration than barrels with pressure points along their length.  You cannot stop vibration, but you can break it up with pressure points.  The ultimate example of harmonic vibration is the Narrows Bridge near Tacoma WA which self destructed because there were no structural elements designed to break up the vibrations amplitude.  All of these elements are relative in that if you change one thing, like velocity of the projectile you may be changing the amplitude to a greater or lesser degree.  Tuning your load to have it exit at the null point in the vibration has helped with accuracy sometimes.  As muzzleloaders we tend to tune our loads for accuracy and possibly we are finding the null point in the process.  Where you rest the barrel becomes a factor because it produces a different pressure point on the barrel among other things.  You can chase this stuff until you are totally crazy and never improve upon the performance enough make the chase worthwhile.  Variables like cross wind blowing on the barrel can have an impact.  Temperature of the barrel also is a factor.  Others maybe hardness of the projectile, and pressure curve with a specific powder lot.  I chose to just tune my load to get best accuracy and accept that. 

[smylee grouch]

This is a very interesting and complex topic for sure. I have been fortunate to be able to shoot with some very good bench rest shooters on the muzzleloading bench rest range at the NMLRA western national shoot and also be a range officer on the same line for the last 10 years or so and have been able to absorb some of the top shooters know how but I have never heard any of them discuss barrel harmonics. It is a coincidence but the week after the NMLRA shoot there is a large centerfire bench rest match on the same range. I get to visit with many of those shooters as a lot of them show up the last weekend of our shoot and we have a mutual curiosity about each others shooting disciplines. As has been already stated, barrel harmonics might not affect the off hand shooter shooting a longrifle but could be a factor in the more exact sport of bench rest shooting.

[Dennis Glazener]

I am going to lock this thread, we have pretty much answered th OP and have drifted into modern arms discussion several times, me being ones to break ALR discussion rules. If anyone wants to discuss ML barrel harmonics please start a new thread.
Dennis