I admit to being new at reloading. Also admit to taking years of physics and calculus and statistics and a lifetime of trying to figure things out.

The recent fascinating exchanges of OCW and Audette etc. lead me to a dumb question that shakes the very basic assumption of figure 8 vs oscillation vs ellipse vs blooey.

On to the question. Have you ever spit out a water melon seed? ever blown smoke rings? That is the basis of my theory of ballistic harmonics oscillation vibration. the watermelon seed smoke ring theory.

When the charge goes off, the best charge selectable by the OCW method will produce an even ignition and combustion with a smooth flat top to the pulse of the explosion. This is as measured against time. Selected powder charges above and below the OCW may have a too-sharp peak, or a skewed curve to right or left along the timeline. These skewed curves introduce unwanted variability into the pulse, and slightest variations in charge screw up the magnitude and the timing of the pulse of the explosion. The OCW will be repeatable, forgiving, and balanced to the case volume, powder type, and primer type, etc.

In the barrel, as the charge ignites, the brass and the barrel expand like my cheeks do when I prepare to spit the watermelon seed. Or as they do when I used to blow a smoke ring. Or as Louie Armstrongs did with the trumpet. As the powder charge expansion is rather quick, the travel of that initial shock wave travels down the barrel faster than the expectorated seed. In this case the bullet.

This shock wave within the barrel is not flat from side to side or from top to bottom, it is not elliptical, it is not a figure 8. It is generally circular, like a smoke ring, except for subtleties influenced by either a rectangular action, a second barrel, bedding and pillar posting, or the front pressure points, etc. I believe, with no evidence, that the reason for the observed figure 8 at the POI, is that the actions of most guns are not evenly susceptible to circular expansion, since the structural member and scope mounts are on the top and bottom they dampen the smoke ring to some other shape. And think of that big old front iron site sitting atop the barrel end, affecting barrel expansion and contraction.

Well now the three dimensional shock wave that shoots down the barrel gets to the end and stops, or vibrates, or rebounds, or GOD knows what. But in any case, shock waves and vibrations are bouncing back and forth from crown to action and back, with primary and secondary and who knows what else, from primer firing, powder ignition, powder movement, bullet hesitation, bullet hitting lands, bullet twist, and all the other things that no one will ever model.

But what we can see, is as these circular shock waves go down the barrel, either the expansion makes the barrel diameter at the crown bigger or smaller than the starting diameter at any one time. And if the bullet leaves the barrel at the right time, it is well confined. And if the bullet leaves the barrel at the wrong time it is loosely confined, and subject to wobble or whatever else may be happening, like some unidirectional movement like barrel lift from recoil.

So either stay with me or forget it and save trying to follow the next part.

Ever have a watermelon seed take a premature entry into the critical orifice? or a late entry into the pursed lips? or into loose lips?

Well you know if the timing isnt just right then it goes short, or wide, or just phooey like a sloppy smoke ring does. And all the theories about OCW and Audette have capitalized on this timimg issue. OCW solves the timing issue by robust charge selection. Audette makes the timing issue robust as possible by adjusting the timing with empirical evidence at the target. I wonder if the BOSS system does not time the bullet release, maybe it simply dampens the shock wave altogether? And maybe the muzzle brakes just dampen the same phenomenom by fuzzing the shock wave?

And the bullet seating depth does indeed take the timing thing down to the best time to exit the barrel, not because the barrel is whipping from side to side, or around in some infinity-shaped figure 8, but maybe because it times the smaller (or larger?) barrel opening at the crown. Hence the critical nature of a perfect circle at thc crown, with both gas blow-by and bullet grip affected by the perfection of the crown.

Now on to the released bullet. Iff leaving a perfect circle, between shock waves, thenn a bullet will select a nice straight path. If leaving the bullet crown through a flattened circle, as in an elliptical shaped barrel, (A flattened smoke ring) the bullet will take any path within that ellipse. And if leaving a very flattened ellipse, the bullets will leave with more of a yaw to their spiral flight.

Further confounded by the spiral trajectory found in flight, from the crown until stable flight is reached, this may explain the benefit of heavy barreled benchrest rifles, not because heavy barrels reduce the sideways "whip", but because the resistance to the circular shock wave from variation of barrel diameter at the bullet exit.

Remember the legendary swedish mauser with its barrel bands? Remember the vertical stringing from placing a barrel onto a hard rest?

Blast away guys, and if this is "so what everyone know that" theory, well like I said, I am only a few years into this stuff. But it may explain why both Audette and OCW BOTH WORK to efficiently find loads that optimize in many rifles.

Jameisters smoke ring watermelon seed theory

If you included "Gibbs" theory of reverse powder ignition? Hey, that's it! You hit the nail on the head!!!!

I just read an article in Varmint Hunter magazine where the author re-capped the load development process given to him by Doug Arnold of Arnold Arms.

From what I gather, Doug recommends looking for the harmonic sweet-spot by charting differences in seating depth(distance from the lands). Once that sweet-spot is identified, he goes on to find the powder charge sweet-spot. He cleans before each volley and uses 5-shot strings with the first 2 being foulers. I'm just learning about this stuff but it seems like a good process.

Arnold's process appears similar to Green788s method but in reverse order. Arnold's method looks to be a good choice for the smallest groups without regard to velocity whereas Green788s method appears to be a better choice for finding the best performing powder/charge in terms of accuracy and velocity. Am I off base on here? Very interesting topic(and well thought out too).

[ 03-02-2003, 22:20: Message edited by: Nebraska ]

Very interesting...

I have heretofore subscribed to the figure 8 pattern at the muzzle, but I have no hard evidence that that is the case. I've seen depictions in a couple of publications that would indicate the figure 8 pattern, but I don't know what method of science was used to decide that this is the case.

So what I'm saying is that you might be right--insofar as anything I can prove.

An engineer that I'm currently corrosponding with likens the OCW charge to the "clapper hitting the bell." If the clapper hits the bell with the same force, in the same way each time, the bell rings the same. So the OCW load has the ability to "ring the bell" the same every shot.

Somewhere during that plethora of barrel oscillations and contortions the bullet will leave the muzzle. My method first seeks to find the charge zone that seems to throw the shots to the same point of impact, and then "depth tune" to get the groups tight.

If I don't misunderstand you, you're saying that more so than flexing to and fro, the barrel actually changes internal dimension during the shock wave's progression. I'm not a physiscist, so I can't argue or substantiate that notion. I suppose it is possible.

The idea that a heavy barrel will resist these internal dimension changes more than a sporter barrel makes sense. But the heavy barrel would also resist the "whipping" action that is conventionally believed to be the pattern.

In any event, whatever is going on with the barrel at the muzzle, a repeatable, resilient powder charge seems able to take good advantage of the situation, and depth tuning of the bullet seems very effective in tightening the group even further.

If there is merit to your supposition, it might be in this possibility: As the main shock wave moves toward the muzzle, the area just ahead of and the area just behind the shock wave would seem to have tighter bore dimensions. If this is indeed the case, perhaps having the bullet exit just ahead of this shock wave would be ideal.

I'll poke around some in books and on the internet and see if I can find any concrete evidence of the actual path and action taken by the typical barrel upon firing...

Thanks for the thought provoking comments,

Dan

May I suggest you mathematically inclined folks quit smoking cigars and spitting watermelon seeds, and read the following article:

http://www.vni.com/books/appstudies/rifle/rifle.html

Then, tell me what it means...... LOL! Dutch.

Quote from the conclusion of the linked article: "The prototype rifle and barrel now are being built, which will provide the measurements that will validate this model. The most significant realization should be small, tight bullet groups across a range of loads and temperatures (which affects internal ballistics), with no adjustments required on the part of the shooter."

Which is to say that the math works out nicely, but will the barrel produce?

If it won't, I believe counted among the problems will be the fact that the computer model assumes that the density of the steel will be totally uniform from breech to muzzle, which isn't likely. (I could be misunderstanding their reasoning, but I didn't see any allowances made for variations in the barrel's density, which will likely exist. It is also possible that this will make no difference, but I would tend to think it would).

Whether the varying effects of recoil on the whole system (when the various loads are fired) will have a spoiling effect would also be interesting to see. Throughout the entire litany, no consideration to the effects of recoil on the barrel's vibration pattern was mentioned. (Unless it got buried somewhere in the barrage of calculus!) And recoil will change when different powder charges are used.

I think the main thing to note here is that we're talking about theory at this point, as the actual barrel has not been made yet. Too, such a barrel would be a bit cumbersome for all uses outside of benchrest.

It will still be interesting to see if this barrel works as theorized. I've seen several such brainstorms never get any farther than the math, though. Seemingly the passion for the project subsides somewhere between the chalkboard and actually building and testing the "rocket."

Dan

Hey Jameister, Must admit the, "Jameisters smoke ring watermelon seed theory.", has more working physics driving it than the Rookiegreen MUC Load fiasco.

Jameister, "I admit to ...taking years of physics and calculus and statistics and a lifetime of trying to figure things out."

HC: Well, that helps explain why you got very close to understanding what is actually going on.

Jameister, "On to the question. Have you ever spit out a water melon seed?"

HC: Yes, many times. Not sure what the number required is to become "Expert Rated", but I'd think I'm in there somewhere.

...

Jameister, "This shock wave within the barrel is not flat from side to side or from top to bottom, it is not elliptical, it is not a figure 8. It is generally circular, like a smoke ring,..."

HC: Well, almost! The Force you forgot to include is(tada) "the rifling". I'd rather not bore a lot of people with the Physics involved, so let's simplify it to - Things in motion tend to resist a change in direction.

Therefore, the bullet(watermelon seed){By the way, don't you REALLY feel watermelon is good enough to deserve 2 "l"s?} is trying to accelerate in a straight line, but the rifling imposes a Rotational Force on it. (Like twisting your tongue prior to spitting.)

Now, the bullet is resisting this Rotational Force and that creates another Oscillating Force Vector. When this is added to what you described as a Circular Force Vector(since they occur simultaneously), you get the Figure 8.

I suppose it would be more confusing to mention the barrel getting shorter and longer(longitudinal oscillating Force Vector) while all this is going on, so I'll just keep that to myself!

Jameister, "Well now the three dimensional shock wave..."

HC: Of course, depending on the particular combination of cartridge(case, primer, powder, bullet) and barrel, you might see increasing oscillations to a specific point and then decreasing oscillations(dv/dt) in all 4-axis(x,y,z, and rotational y).

This can be likened to the changing harmonic "head oscillations" while spitting the seed after consuming a 12-pack of Pabst Blue Ribbon fuel.

Jameister, "...bullet hitting lands, bullet twist, and all the other things that no one will ever model."

HC: Well, what can I say. You recognized that it was there, but failed to include it within your spitti...uh, otherwise fairly good logic.

You can not choose to simply "ignore" a Force Vector. (You are hereby accredited with a few demerits over this issue. But, no where near the MUC Load level!)

Jameister, "Ever have a watermelon seed take a premature entry into the critical orifice? or a late entry into the pursed lips? or into loose lips?"

HC: Probably - after the PBR fuel consumption - but who remembers???

Jameister, "Audette makes the timing issue robust as possible by adjusting the timing with empirical evidence at the target."

HC: Absolutely correct!(Demerits removed.)

Jameister, "I wonder if the BOSS system does not time the bullet release, maybe it simply dampens the shock wave altogether?"

HC: If by "shock wave" you mean harmonic(s), yes!

...

Jameister, "And the bullet seating depth does indeed take the timing thing down to the best time to exit the barrel, ..."

HC: So far, so good!

Jameister, "... not because the barrel is whipping from side to side, or around in some infinity-shaped figure 8, but maybe because it times the smaller (or larger?) barrel opening at the crown..."

HC: Improper conclusion.

Jameister, "Hence the critical nature of a perfect circle at thc crown, with both gas blow-by and bullet grip affected by the perfection of the crown."

HC: This is actually a totally different issue. But, I can see how you got "mislead" toward this conclusion.

...

"Jameisters smoke ring watermelon seed theory."

Hey Jameister, Try incorporating the "twisted tongue"(rifling) into your Logic and I believe you will get to where you ought to be.

Good watermellllon hunting and clean 1-spit shots to you!

Holy F(x) that article gave my little mind a multiple bending moment..............when you guys figure it out, let me know would yah. Till then I'll be at the bench dumping measured amounts of powder into prepped primed brass then seating projectiles consistantly in hopes of keeping the holes in the target very close together.......

Jameister:

Selected powder charges above and below the OCW may have ..., or a skewed curve to right or left along the timeline.

Heh ,You are way ahead of us here in the 3rd dimension ,I just came back home thru a wormhole myself

In my experience (experimental chemist) we usually fit the theory to observation,if needed with a few fudge factors.That way we "understand" that the chicken came before the egg,or at least some believe so c fervor.

All in good humor,I wonder why we dont have high speed photography to at least document the harmonics

sheephunter

"All in good humor,I wonder why we don't have high speed photography to at least document the harmonics."

I believe this has been done, and I believe this is where the "infinity" or "8" pattern was verified.

I could be wrong, though. Just ask my buddy (the now seeming mad-scientist) Hotcore!

Dan

Hot Core,

I'm just learning about reloading but in the short time I've been here, I've noticed you follow Green788 around and make personal slams in an effort to get his goat. How come? I can see disagreeing with somebody or even not liking someone but geeeez!!!! I've talked with Dan on the phone and he was very friendly and doesn't seem to be the kind of guy that would attract such animosity.

I am glad things like the figure 8 can be figured out with a camera. Now, how can we get someone to take a series of photos from directly in front of a firing barrel?

Seems like there could be problems with that one.

in answer to a few questions: yes spitwads count, no I am not from a time warp, and I have no clue how to capitalize on teh concept that the barrel bulges like a snake with a rabbit in it. And uf that snake shudders from head to tail at a different rate than the rabbit goes down the same path, I dont know what difference a spiral rifling will make.

But then I also dont know why smoke stacks have spiral wind vanes on them for stabilizing against winds either.

I just got back from the range, and at least now I have a reasonable theory as to why every 10th or 20th shot ends up a few inches outside the expected group.

Of course, I am trying to regulate for old double rifles that defy most of the few reloading rules that do exist.

thanks for the responses guys, and this is kind of safe ground since it is all conjecture for me.

One thing I do know: It is not so simple as ringing a bell with a clapper.

You caught that spit-wads comment! I took it off the next day hoping you hadn't read it. Of course it was in fun but you'd put so much effort into your post, I didn't want the thread to get side-tracked!!

Jameister, agreed... It's much more complex than "bell ringing," but the analogy that was offered to me by the engineer I'm currently corrosponding with did not seek to explain all of the intricacies, but rather just to give a basic idea of what we're after: a consistent, repeatable force from the powder charge. While the barrel will gyrate with much more variables than a bell would, its gyrations (if all is well with the rifle) will be repeatable if the barrel is "struck" in the same manner each time.

Nebraska, thanks for the kind words... I have mulled the Hotcore thing over for quite some time now, and I can only conclude that he is intimidated in some way by me. Unfortunately that sounds just smug as hell, but he has forced me to conclude that.

I enjoy sharing my experiences and findings with you folks here. I try my best to avoid confrontations and counter-productive arguments with fellow members, and for the most part, I've stayed in the clear. Hotcore is the only exception. Oh well...

Till next time,

Dan

Green, kudos to you for taking the high road.

So here's a thought. In order to tune for a BOSS equiped rifle, the emphasis would appear to 1st be on determining a stable charge weight. This is where the OCW philosophy fits, however I believe that the harmonics factor cannot be removed unless one shots more than three shots for each load. With a BOSS equiped rifle, harmonic tuning is a simple thing, therefor the other factors such as shot-to-shot velocity consistency is more what the handloader needs to concentrate during load development. This leads me to believe that using a chronograph is the best way to truly get the powder sweet spot (again this is for BOSS rifles, those rifles without a BOSS need to work out harmonics in both the OCW work-up and bullet seating).

The chrony's I've used have a 1% error band so at 3000 ft/s we have a 30 ft/s error.

So the question becomes: which has the less error for calculation purposes 3 shots and measure the target, or three shots and review the chrony data.

I've recently reviewed the Reality-Based Load Development and reviewed the data. When the analysis is complete I have a different ideal charge weight based on soley the Chrony data than on the target data.

Once the charge weight is determined, a fine tune of first bullet seating depth, then BOSS tuning should complete the tuning.

[ 03-03-2003, 11:27: Message edited by: AlbertaBound ]

You guys have wayyyyyyyy too much time on your hands!

Hi
On figuring out how the barrel harmonics look , one could take a barrel mounted laser sight and point the laser dot on a plain surfice at about 100 yards and take a fotografy with a long exposing time just before you take the shot ,
this must naturaly be in the dark.
That should show the harmonic pattern.

Anders �sterberg

You could take the high-speed photos through a mirrow set at a 45 degree angle to the muzzle. It would be destroyed but you would have the footage. However the muzzle blast would obscure the muzzle at the time of the bullet exit, but you would see a lot during the time before.

Hey guys,

Regarding chronograph data, I'm hesitant to say at this point whether the tight numbers will indicate the OCW zone. A new found friend, who is an engineer in Seattle, WA, is doing some testing along this line, and his preliminary conclusion is that the OCW zone is not commensurate with the tightest extreme spreads.

Here is why I believe that is the case: Keeping in mind that the muzzle is "whipping" from side to side during the vibration pattern, it is fairly easy to see that the muzzle will be moving from "perfectly straight" to "fully bent," and then back to the other extreme.

During the nanoseconds in time that the muzzle is moving through the perfectly straight part of the vibration pattern, the bullets will not have to "curve" to exit the muzzle--they'll just waltz straight out of the bore. The closer to perfectly straight the bore is when the bullets are released, the tighter the ES will be.

However, the muzzle reaches the extreme points of the whip cycle moving very fast, and it slows down very fast. Bullets being released in this time window are going to show less than magnanimous extreme spreads, but that's got nothing to do with the powder charge.

A more uniform charge, one that is igniting and burning very consistently, might well--by mere chance--have its bullets exiting the muzzle when it is approaching one "fully bent" extreme. Actually, this area would be just ahead of what we strive for--the "sweet spot." But because these very uniform loads had their bullets arriving at the muzzle when it was approaching extreme bend, the velocity numbers began to drop noticeably for the "late arrivers."
To clarify, let's say you have three charges of 44.3 grains of XYZ powder loaded. We must accept that there will always be slight variations from one cartridge to the next, no matter what we do. These three 44.3 grain shots would have a tighter extreme spread if they were released when the muzzle was fairly straight, as opposed to being released when the muzzle was approaching the extreme end of the whip cycle.

And we've been seeing this played out on the targets. The tightest extreme spreads are not generally yielding the best groups. If you "depth tune" the bullet to take advantage of the barrel's best node, then those good chrongraph numbers will likely not repeat. It's possible, I suppose, to have a unique situation or two, but as a rule, I would not rely on chronograph data for selecting the OCW charge.

Alberta Bound, I have no experience with a BOSS system, but I'm familiar with how they work. It would be very helpful for me to know if, after tuning the BOSS unit, the ES changes. If my thinking is correct, I would say that the ES would open up as the node is approached, and then likely tighten back up as the node it "topped." Perhaps input from you, compiled with that of other owners of BOSS equipped rifles would lead us to some understanding.

Anders,

The laser idea sounds interesting. Of course the light path would string upward to follow the recoil arc, but if that could somehow be factored out, I suppose it would be possible to learn something there. It never hurts to experiment--we always learn something...

Dan

It's not as simple as ringing a bell? I thought it was, but maybe someone out there can explain bell ringing to me. Say you have a bell, and you have a way of observing surface waves on the bell. Now you strike the bell in different places. Is the vibrational pattern different depending on where it's struck? It was my understanding that there isn't a significant difference, but I really havn't seen experimental evidence on this.

Jameister

I was ready to discount your theory, until I actually calculated the expansion of the barrel due to pressure, and found that it would be slightly over .001 in bore diameter increase for a typical barrel configuration and pressure. How much that varies, however, with pressure waves, is the subject of conjecture.

I'm going to say something here that will raise a lot of hackles, but needs to be said. I am really tired of reading all this technodribel. I, like JAMeister, spent years studying science, and have worked as a professional engineer for over 30 years. The people who post all these "theories" need to spend some time developing the underlying equations to support them. Instead, they seem to spend their time writing long diatribes in which they basically present their view of "how things happen" and attack the other's viewpoint. So what? With no proof or supporting calculations, they are just someones passing thoughts. Stop BS'ing and provide the hard data and support. If you can't, stop posing as experts.

Regarding the vibration pattern of rifle barrel's, and what I've shared here...

None of this is theory, it is fairly well known--at least to those of us who have taken an interest in such matters. (And that is not aimed as a slight to those of us who haven't).

Countless articles and books on rifle accuracy over the years have all dealt with the physics of the barrel's vibrations. While (as I admitted earlier) I've done no such tests to confirm this pattern myself, I'm inclined to sign on to the scientific consensus. And all of my practical experience does in fact support the basic "infinity" vibration pattern (at the muzzle) of the conventional rifle barrel in action. I'm not here to argue with intellectual giants.

(By the way, yes, the barrel does swell along the bullet's path, like the analogized snake eating a rabbit!) More fact, not theory--for the record.

And now this...

I see these threads as being much like television channels. If something doesn't interest you, skip to something else that does. That's what I generally do... (And it can save you a lot of aggravation!)

If any of my fellow members are interested in the intricate matters of rifle accuracy, as mentioned before, books are abundant. I like the old Warren Page volume "The Accurate Rifle," and while my jury is still out on Harold Vaughn's "Rifle Accuracy Facts," I will at least say that there is some wheat among the chaff there--from what I've seen so far. Precision Shooting magazine is seemingly the industry standard of these matters, and Rifleshooter gets a little technical and enlightening now and again.

If there is something more I can do to further clarify my points, I'll be glad to... (short of being the Google link liason, that is-- Y'all are on your own there! )

Till next time,

Dan

Well, basic trig was a bit beyond me, so I can't delve into the math of the thing. But...

I do know that by the time I had all this arcane stuff completely worked out down to the last quadratic equation, I'd also have a flinch that obviates the whole mess!

Till then, I'll continue to work up loads until I can stay within "minute of critter" and call it good.

(Seriously, the theories are fascinating to read, even if they may have no ultimate practical application.)

I think my point in my first post may have been misunderstood. I too am interested in the technical side of accuracy; unfortunately it is not handled very technically in any of the volumns mentioned. To claim Warren Page as a technical source is like claiming an air force bomber pilot is a nuclear warhead specialist. What is covered in most of these types of books is a study of the empirical results of accuracy work, with enough technical "shoutouts" to add an aura of competence. From a shooter's standpoint, empirical results are all that is important. No two rifles are the same and they don't perform the same. What reloaders need to focus on is the identification of accurate ammunition for their particular rifle. Do these different methods work? I'm sure they do. Do they work because of a lot of theories which have been put forth? I don't know, and I don't believe any of the posters know, since none of them, to my knowledge, are professionals in that field.

The article referred to by Dutch is the only quotation of any relevence I have seen in any of these posts. It appears to be a fine example of modern, state of the art modelling. (Did you know that Formula 1 teams no longer use wind tunnels? Their CFD capabilities have rendered them unnecessary.) If you read through the article, you will find that their model addresses every point brought up in this string, such as barrel expansion (both longitudinal and radial; the longitudinal component was missed in the watermelon seed theory. It would equate to extending your lips as the seed moved outward.), unbalanced vibration due to sights, muzzle misalignment etc. The response to this quotation was basically, "Yeah, but let's see 'um build that barrel before we pay any attention to that work."

My objection to this type of thread is that shooter's who have absolutely no knowledge of the subject will read these lengthy posts, and decide that they are not capable of understanding the subject, ergo, they cannot be effective reloaders. The fact is that, while interesting, none of this has any pragmatic impact on the production of quality, accurate ammunition. If every shooter could model his rifle perfectly, the only thing he could do to improve the accuracy would be try different bullets, powder charges and seating depths. Modelling might make the search easier, but would take longer than developing the loads. Modern CFD software generally runs on desktop supercomputers and often has solution times measured in days, or weeks, for each run. That's not very practical for the average reloader, and he shoudn't be made to feel inferior over it.

I'm sorry if my response seemed abrasive, Art. Let me beg your forgiveness, and take a better crack at civility if I may...

Us laymen are offered, by more than a few of those presumably in the know, a "model" if you will, of what the muzzle of a rifle barrel does when the cartridge is fired.

This model has endured because it seems to be the case for the majority of barrels. Exceptions are extant and noteable, I'm sure, but we see circular and arcing patterns displayed with such regularity on the target that it is very safe to assume--even in the face of no scientific evidence I would say--that at least part of the vibration whip is circular or more likely, elliptical.

Since you are better studied in physics than I am, let me ask you this: Since it seems a veritable given that at least part of the muzzle's pattern is somewhat circular, what is the liklihood that this circle is the larger part of the presumed "figure 8?" I ask this because it doesn't seem likely to me that the barrel would strike a circle, beginning in the "at rest" position, without ever deviating beyond the static point and toward the opposing side. Is this making sense?

Here's a crude depiction:



The green dot represents the barrel's static position (before firing), and the "A" circle or "node" would be the main circular or elliptical pattern that I hope we can agree exists.
Considering that the barrel is beginning motion at the green dot, and moving first into the "A" node, what do you believe the liklihood would be that the barrel would enter the "B" node area for at least some period of time and space? My own thoughts are that it would strike some pattern in the "B" area. The "B" node would likely deepen as the "A" node became more elliptical.

Let me know what your thoughts are, here. I honestly believe that a basic understanding of physics--especially when augmented by those with formal education in such subjects--will help us all to gain a better understanding of what the vibration node would look like.

By the way, if the "B" node exists--and I believe it does--it would be the better of the two nodes for accuracy, being smaller...

Dan

Dan,

I'm glad to see, how this thread is getting more oriented to study the real phenomena taking place, and especially your kind attitude at this.

As said many times before, I appreciate this kind of cooperative and useful work, since instead of the previous posts.

Keep up the good work

Thanks, Gus...

I'm sure we can find common ground for good communication here. We've all just got to keep heterodyning until we find a common harmonic frequency!

I enjoy this kind of stuff, I must admit--but I never want to mislead or confuse...

Take care, and be well...

Dan

Hotcore, or any one else who wants the now 50 dollar reward:

Find the post where I called Hotcore a liar (prior to his accusing me of such), and I'll send them the money. I'll send the 50 bucks for even one such instance to any member here, and Hotcore's membership here is much older than mine, so all of my posts regarding him are in the archives.

The truth is, I've never called Hotcore, or anyone else here a liar. That's childish to do such. I have no idea what he's doing here... Sometimes I think he may have me confused with someone else, and sometimes I think he just has a very colorful memory ...

Folks, if you're not into the tripe, just skip the link below, but I believe this is where Hotcore first got the bee in his bloomers...
http://www.serveroptions.com/ubb/ultimatebb.php?ubb=get_topic;f=6;t=006044#000026

I see stuff posted by fellow members all of the time which I don't fully agree with (Things such as "My rifle hates Remington brass" and My rifle only "likes" 4350." But that's no call to trounce someone. Yeah, I know I was a bit hard on Hotcore in the link above, but I don't imagine anyone will say he didn't ask for it!

Now, back to the topic, dammit!

Dan

Here's where we get in trouble, we are all talking about opinions. You asked for my opinion, so here is a short version.

Number one, I am not sure the unrestrained muzzle would generally be a node of a barrel in pure vibration(which we certainly don't have). I also highly doubt that the green point shown would ever be on the edge. I would be highly surprised if it weren't near the center. As you pointed out, you don't have a pure single axis vibration, if for no other reason than you have the pressure induced vibration and the asymmetric force from the rifling. What you likely would see in a model of a free floated barrel is a unidimensional vibration which precesses around the axis of the bore.

I also would be surprised if the B circle would normally lie outside the A circle. Normally vibrations don't vary much in amplitude, so to find it ouside of the normal range would be odd. It wouldn't be odd to find the bullet path there, though. I would agree that, for any given region defined by any small circle inside A, which I think is the region described by the total vibration cycle, you would at time have bullets coming out at that point. If you do this consistently, and the small region is the one that induces the most accurate external bullet flight, then you will achieve the best accuracy. This is not a revelation. Barrels vibrate. Do it consistently and minimize the vibration (heavybarrel, short barrel, BOSS device) and you get the best accuracy.

To me, that's more than enough conjecture. None of it leads to any better performance. What you seem to have done in your method is to quantify in an organized form a system that has been in use for years to develop loads. You have a system to find the best powder charge and then the best seating depth for a given bullet/powder combo. I think this is admirable and could save inexperienced people a lot of floundering around. Jack O'Conner once said that he had written a column on "How to Sight in a Scoped Rifle" at least 17 times, but there were still people who thought it enlightening. I will have to say that I think things could be done a little more systematically. I don't buy into the round robin method, for instance. I think this could lead to problems with very light barrels. I would rather see group tests with consistent cleaning/cooling cycles. However, it's your method and if you think empirically it works, that's fine.

I really believe that what draws all the criticism and causes the rift is the constant need to attach some psuedo-theory to what is observed. Just concentrate on the development method and forget the theory, which is much to complex to elucidate by study of a few shooting books and shooting at a target. I think a lot of people can benefit from a consistent load development method. What I see however, are posts from beginners prattling on about whether someone thinks their barrel is going through a high or low acceleration phase of its vibration pattern at a given loading. They are missing the whole point which could help them, which is be consistent, home in on results and change one thing at a time based on results.

A good example is the report by your friend that the best load doesn't necessarily yield the lowest standard deviation in MV. This is not big news. Benchresters new this 35 years ago. A lot of empirical work has shown that consistent powder charges are probably the least important variable in accuracy with most rifles. A lot of things such as neck concentricity, case volume and primer pocket/flash hole consistency are much more important. A survey of any loading manual with standard deviation data will show that the most accurate load noted is often not the one with the lowest SD or ES. What you do see is that short fat cases such as the 284 Winchester, the PPC and the new short magnums seem to have, across the board, lower SD's and ES's. Why not just accept this body of data, don't worry about why it happens, and concentrate on developing and documenting the system. The why it happens is of no real concern and likely beyond any amatuer attempt to discern.

Thanks for the thoughtful comments, Art.

I think I blew the verbal description of the A/B pattern a bit.

What I was trying to show with the circles is the supposition that the barrel vibrates from one extreme to the other during the vibration cycle. In other words, rather than just vibrating toward one extreme, and never moving back to the other side of its static point, it moves to one extreme, returns to cross the static point, and enters an area opposite the main node. The twisting effects of the rifling bullet and other subtleties would "ride" all of this, perhaps looking like the very crude red line inside the original figure:



I call this the "massacred snowman."

You're right that the true pattern would be more complex, laden with harmonics. I've always been of the opinion (there's that word again) that the main vibration node had the most to do with accuracy--that the resultant harmonics were less a factor, if indeed a factor at all.

But anyway...

Regarding the round robin method of load development, I do recommend "proof testing" at longer distances with low, mean, and high charges after identifying the suspected OCW load. (This is all mentioned at my website). I outline my reasons there for the round robin method, so I won't mention them again here.

Stay in touch, and thank you again for your thoughts and knowledge.

Dan

Just checking back,the thread has not developed into more insightful knowledge
I agree wholeheartedly with most statements,if I understand them correctly.I shall enforce this my understanding by restating my previous religion in these matters:
we usually fit the theory to observation

in other words :it absolutely matters not (although it might be interesting academically)how the barrel vibrates in its 3 dimension,and another complicating factor:how the bullet released thru the worm hole but subjected to a violent whip ,will have a momentum that will throw it from the axis,even when released at the node.
I surmise this is a very complicated vibration model.I further surmise that this is more complicated than simple math or physics,which usually describe distinct events(in my experience)
we are hitting what I call engineering math,which typically uses experimental fudge factors to APPROXIMATE the experimental findings.

For all the above- we might as well agree that there is a little device in the barrel that makes the bullet deviate from the linear.

As said by others:this is irrelevant as it has absolute no bearing on load development- none.

We are still faced with finding the right powder load for each bullet for each rifle,100% experimentally,no formulas to help us.

So why spent time on a theory that will not assist solving the practical task at hand?

sheephunter

"As said by others:this is irrelevant as it has absolute no bearing on load development- none.

We are still faced with finding the right powder load for each bullet for each rifle,100% experimentally,no formulas to help us.

So why spent time on a theory that will not assist solving the practical task at hand?

sheephunter"

Like someone said: We have too much time on our hands.

Seriously, I am loading for old double rifles, and the ability to determine which problems to tackle with load development, and which to tackle with mechanical tweaking, depends on the cause of the ballistical performance. I have a challenging overunder 8mm right now that prints the top barrel between 3/4 inch and 2 1/2 inches to the left of the bottom barrel at 100 yards.

For no real reason, I want to have the two barrels to converge and to superimpose their groups perfectly.

Some bullets run closer together, some further apart. All are offset, so far. Before I go the seating depth routine, the DROCW (double rifle optimum charge weight= regulating velocity)needs to be determined, and then the EBOCW (each barrel OCW), and then the combined seating depth so that one load optimizes both barrels. Kind of like employee wage rate negotiations. Keep the individuals happy and still make profits for the group.

Anyway, If the twist of the rifling makes the barrels cant to the side, then its a hardware solution. If the offset is because of exit timing its a load development issue and I am hundred of dollars better off.

This is the real reason for this whole crazy post!!

If you think the reloading and load development is too easy, get you a double rifle and prepare to eat humble pie!!

Jameister.

PS Thanks to all for makeing this a fun one. I did review the technical reference, and even though exposed to calculus, and even used it twice in thirty years, I would rather not try and go there. Those guys did make one entertaining statement though: based everything on one assumption, that is perhaps too simplified. Like my watermelon seeds.

If the contributed statement of .001 inch radial expansion from the charge is correct at the muzzle, that would only be .1 inch at the 100 yard target. Appreciate any more on that one.

Damn this is getting deep what with the optiomal pucker of a watermellon seed spatooie and all. Seppen that thar idear dont werk so good with the werk yer whistle theory, beins that we'ns all gots our own placement of our theeth (that is usn what's still got um ) an so the OPTIMAL whistle that one goes a makin aint always the same!! cause o lil differenc's in our own makins of a whistle, an Ill be tootin if'n that dont apply to Watermelon seed spittin an smoke ring a blowin too...

Dan,

have you gotten Harold Vaughns book yet? I can't put it down myself. Best book I've read concerning these things and alot more.

I would add a few things to what's been said so far, Dan is not too far from what Harold has found and uses basically the same POI shift to determine where the node is. The other thing I found most interesting was this, and it explains why a larger ES might not be so critical; I'm sure I'll botch his explanation up a bunch, but you'll get the idea.

First, Harold said that he found that horizontal dispersion was about 1/3rd of what vertical (.8") proved to be. Horizontal dispersion was said to be about .27". To him, this was attributed to the lack of horizontal asymmetries, the gas vent hole being the only obvious one.

Forget it, I won't try to explain the rest I'll let him. Here is a excerpt I thought a few might find interesting from begining of the chapter on barrel vibration in "Rifle Accuracy Facts" by Harold Vaughn;

"Well, in this work we are going to try to find out just how and why the barrel vibrates, and correct the cause of vibration. We will do this by measuring the moment acting on the forward receiver ring which causes the barrel to vibrate and then we will make corrections to the rifle that removes the forces that cause this driving moment. At the same time we will measure the barrel muzzle vibration in the vertival plane with an accelerometer just to make sure that the vertical vibration of the muzzle is reduced. We will also use a barrel vibration computer simulation code as a guide in the design of the instrumentation and to evaluate the effort of barrel vibration on accuracy. While the data presented are restricted to the vertival plane, bear in mind that similar vibration at smaller amplitudes occurs in the horizontal plane due to the same driving moments or forces.

In the course of this investigation we will find that the moments that cause barrel vibrations result from the recoil force acting on the recoil lug, and from the bolt thrust acting on the bolt lugs with uneven engagement, and from forces generated by the cartridge case acting on the receiver that is structurally unsymetrical. We will first eliminate the recoil lug moment with a special bedding device and then reduce the structural asymmetries in the action, resulting in a large reduction in the forces and moments that cause the barrel to vibrate.

All the work on the standard and unmodified rifle will be conducted on a Winchester 270 cartridge but is applicable to any sporter. At the end of the chapter the 6BR, 6mm Remington and the 6PPC is involved.

Now a note to the reader: this chapter is one of the longest and most complex in the book. However, every effort will be made to explain everything in physical terms so that the information should be clear to the reader without a technical background. So, hang in there!"

He goes on to say, one slope of the node is best to work on and not the other. Groups were plotted to follow the sine wave, which indicates the barrels vertical deflection, and they followed up and down, right together as loads were developed. Here is another quote from him reguarding this negative slope as the proper place to work on.

The vertical stringing of the group size is at a minimum below 3100 fps and above 3300 fps. This correlates with the negative slope of the sine wave, and I beliaeve this is to be expected. If the muzzle velocity is higher than the mean for the group it would have alittle less gravity drop and normally impact a little higher. But, if the gun is operating on the negative slope the higher shot will be corrected downward to the group center by this high frequency phenomenon. The best place to shoot is just past a positive peak on a the curve." (node) "We have found that the amplitude of the sine curve is less (about half) with the free recoil method of shooting than it is with the firm hold method."

His work is a good start to what many should and likely will continue to investigate and test. His perspective on things is new to me in many areas, and I find the work Dan is doing to be along some of the same lines concerning point of impact shift and such.

Most people work up a load many different ways and alot of them have no idea how to make sense of any of it, alot of them don't even care so long as it shoots ok to hunt with, to each his own though. Good luck with whatever way you choose. I enjoy the interesting theories and observations from all of you, whoever's modified method or whatever you call yours.

HotCore,

Dan's method doesn't even come close to Audette's method, that I can see anyway. He shoots groups of three at mostly 100 yards in a round robin fashion, how is that close to a large number in a 300 yard group of Audette's? How is Dan's method unsafe to newbies? I think it would be quite helpfull to someone learning how to develop a load, it at least has points to consider if you are doing so and use another method.

I know you are not going to stop brow beating him, but why state your case over and over again on every thread concerning his method of load development. Are you afraid people might see Dan for who he is, and they just might like him, and you wouldn't be able to stand that? Come on, you've lost this battle, know when to give up. Can you not see that?

I've come to know Dan for his kind and helpfull manor, and yes his load development also, but what stands out about Dan is his personality most of all. Every time you post on "one of his load development method threads", you discredit yourself way more than you ever do Dan.

Just gotta LOVE this forum

R-WEST

Vaughn sounds like a good book!!! Hope it has data to show all these theories!!

thanks to all.

Jamie