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Elliptical Swerve

I interpret it as wobbling with tip direction, but not directly deviating in a coning motion about path.
Imagine how much energy it would take to physically move a heavy bullet traveling ~2900fps with corkscrew displacement around path, in sync with it's RPM, with any significance.
If you had a 8tw barrel, the bullet would need to be deflected one way, then another, then another, then another, etc, -enough to physically exist AROUND intended path respectively -every 8".
No,,,
It's an error that in summation reduces precision, because it's causing irreversible deviation from intended path. But this OVERALL, and in abstract, one direction or another.

I probably shouldn't word my views so strongly, but I believe the 'falling asleep' misconceptions are detrimental to the shooting community. It's the notion in itself that needs to forever fall asleep.
Bryan's video is very useful for this, but it's often taken in misconception.
Maybe you can get Bryan to tell you that Epicyclic swerve causes improving precision with distance, but I seriously doubt he would suggest it. I think he'll tell you what I'm telling you.
 
Hmm... Puzzling for sure...
I think I was picturing in my brain something similar to a gyroscope... that the bullet creates it's own force (would inertia be the right word??) due to it's fast spinning motion which then gives it the ability to entirely (not just the tip, but the entire bullet) follow an ever-shrinking/ever-stabilizing corkscrew flightpath, independent of any other force exerting itself on the bullet (wind, gravity etc...). An aspect of angular momentum??

Man, I dunno... Head hurting... :D

-Clint
 
I am no expert and will not claim to be on this subject. But could these thoughts not be possible?

We agree that the "wobble" impairs accuracy right?

We agree that once the wobble goes away the bullet is on a truer path right?

So is it out of the realm of thinking that a rifle with "bullet wobble at the tip" or "elliptical swerve" at 100 yards shoots a 1" group at 100 yards, or 1 moa. Then soon after stabilizes, falls asleep or what ever, and is on a truer path and is now on a more accurate path. So it holds its path and now shoots the same size (1") group at 200 as it did at 100. Now the rifle is shooting 1/2 moa at 200 and 1 moa at 100.

The last EDGE I set up I was sitting there fighting this at 100 yards. The rifle shot 1" with many load variations. Many consecutive groups at 100 yards that measured 1". I took the rifle to 200 yards and guess what? The same loads that were shooting 1" at 100 were also shooting 1" at 200 yards. This was tested further with more of the same ammo and the rifle was indeed a .5 moa rifle at 200. It also proved to be a .5 moa rifle at 400, 600, 800, and 1000. Take it back to 100 yards and it will shoot 1"

My old tried and true 338 LM was the same exact way with both 300 gr SMK's and 300 Bergers.

A 7mm -300 I built with a 9 twist and 180's same thing but a bit tighter. That rifle would shoot all groups at 100 between .8 and 1". I took the rifle to 300 yards with my favorite of all the loads tested and guess what. Three consecutive groups just under 1" (.3 moa at 300 yards .... .8 to 1 moa at 100 yards)

I may not know what is going on. But I know these instances did happen. I make first round cold bore hits at a mile and beyond quite often. So if you are going to say I need to learn to adjust out parallax then I would probably disagree.

Mike, I am not looking to be stubborn, but if you had seen what I have, you too would believe what you have seen with your own eyes too. Call it what ever term you want but this did happen and these are only 3 of the instances. I have heard of other that also have seen this very same thing. Is it right to just say we are all imagining this? I think not.

For what it's worth, " that's my story and I'm sticking to it"

Jeff
 
Bryan himself posted on the first page of this very thread that the 'swerve' is only a fraction of a caliber.
I think he is saying that as soon as meplat points one way, low pressure on that side nudges it to correct itself in all directions in its circular motion. I think all these self corrections eventually cancel these tendencies therefore 'asleep' .

The hole in the paper may be slightly larger than bullet diameter. ×5, ×6, ×3 holes. But not huge horrible groups.
 
Unless there is zero atmosphere I don't see how a projectile experiencing yaw wouldn't experience a very slight change in direction; and then continue again, and again, and again. I wouldn't expect a net change over several cycles of pitch and yaw. Can someone explain how a bullet in an atmosphere experiencing yaw would not have the center of gravity move off path even the slightest?
 
CB11WYO said:
the bullet creates it's own force (would inertia be the right word??) due to it's fast spinning motion which then gives it the ability to entirely (not just the tip, but the entire bullet) follow an ever-shrinking/ever-stabilizing corkscrew flightpath, independent of any other force exerting itself on the bullet (wind, gravity etc...). An aspect of angular momentum??
Click to expand...
Gyroscopic energy is angular. It's not displacing actual bullet position.
From Bryan's book "Stability is the ability of a projectile to maintain its point forward orientation in flight, and return to that orientation if disturbed"
Note 'orientation' -not physical position, nor direction.
The resulting and possibly biggest energy in play with this wobble is drag.


Broz said:
We agree that once the wobble goes away the bullet is on a truer path right?
Click to expand...
No, this is what needs to be erased from our thinking.
It's path was affected by earlier deviations. Degrees of error in path(in MOA).
There is nothing in this realm that would put a free falling bullet back onto original path (correcting those errors).
It doesn't happen.

I can absolutely relate to shooting better in MOA at distance. As I am one of them freaks that does this consistently. Precision for me? 100yds is bad, 200yds is worse, and then every range to 600 is improved. On a calm day I can and likely would shoot tighter groups(in moa) at 500yds, than 200yds. Also, like fellow freaks, I cannot prove the cause.

So far I'm hanging my hat on parallax, which is easier(for me) to set precisely at 500yds, than at 100yds.
After all, if parallax isn't exactly right at 500yds the target is a bit blurry, the reticle swings wildly. Easy to detect.
But at 100, parallax can be off and my freaking brain can easily pseudo-compensate for it.
In the past I reached for other things, they all fail tests.
 
Mikecr said:
No, this is what needs to be erased from our thinking.
It's path was affected by earlier deviations. Degrees of error in path(in MOA).
There is nothing in this realm that would put a free falling bullet back onto original path (correcting those errors).
It doesn't happen.
.
Click to expand...

If something was there that effected its path earlier on, then that something goes away, is it not fair to say then from this point on it is on a truer path? I never said or meant to imply that it goes back to anything, or any errors are corrected. Or that the errors from earlier flight problems were not still there. Just that it settles in and the wobble that was effecting flight earlier is gone and from this point are not effecting it any longer. And allow it to fly a truer path now that the flight is smoother.
Not eliminating damage done at the first 100 yards , but not inducing further damage as it has settled down for a smoother flight. Thus the reason I see a 1" group at 100 and a 1" group at 300. No errors are corrected, or "steered back" just not getting worse as it is over now.
Jeff
 
There is no 'truer' path, the deviation errors are angular.
1/2moa of angular error at 100 is atleast 1/2moa of error further on, usually more. It will never be any less, as this is now the new path.

Think of it as wind deflection.
An early wind changes bullet path sooner, and this results in more distant error than late wind. The bullets deflected path will not get 'truer' once the bullet passes into calm conditions. It just keeps truckin off on it's new path(with that angular moa of error).
The damage is already done, and there is nothing to undo it.
 
Mikecr said:
There is no 'truer' path, the deviation errors are angular.
1/2moa of angular error at 100 is atleast 1/2moa of error further on, usually more. It will never be any less, as this is now the new path.

Think of it as wind deflection.
An early wind changes bullet path sooner, and this results in more distant error than late wind. The bullets deflected path will not get 'truer' once the bullet passes into calm conditions. It just keeps truckin off on it's new path(with that angular moa of error).
The damage is already done, and there is nothing to undo it.
Click to expand...

I think then I will have to agree to disagree. It is an elliptical error and we do know that there is a force to correct the point at RPM. So if it corrects itself back and forth in an elliptical motion it will indeed be there until it settles down. Then I believe it does indeed settle down and fly a slightly truer path. Like I first said, I am not expert but I do shoot enough to know something happens as per my previous examples.

I guess it doesn't really matter. I was just offering real experience for discussion. In the end I can still hit a cold bore target at 1 mile on a pretty good percentage. So the way I have been dealing with it works for me.

Thanks.

Jeff
 
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I have the same notion as Broz here. I wonder if the terminology may be the difference here. What if we say that the bullet becomes more consistent in it path after some distance?

Steve
 
I think epicyclic swerve may not be responsible for increasing angular accuracy all on its own.

I personally believe lateral throw off ( along with bullet imbalance ) to be to reason for epicyclic swerve and increasing angular accuracy as distance increases.

Im no physicist nor do i have any sort of education that should justify any of you to listen to me. Im only offering my idea.

We all know long heavy bullets are where we see this happen the most, and we also know controlling run out with long heavy bullets is very difficult. Typically these bullets have long boat tails too.

The chance of the bullets being perfectly balanced is very slim and the chance of the bullets engraving the rifling straight and true to its vector of travel is even more slim.

This leads me to believe the center of gravity could easily be misaligned with the bullets center or rotation as it travels down the bore of our fast twisted barrel. Upon exit the bullet experiences lateral throw off to a tanget of an arc of rotation of the bullets center of gravity ( picture a easterner throwing a rock with a sling ). Now at this same time the muzzle blast is racing across a bullet not pointed the direction its traveling as it is spun at a ridiculous rate and now no longer contained by the bore.

I think this action is just like mike says and a constant through the entire bullets flight. But the forces behind lateral throw off and epicyclic swerve pale in comparison to the forces propelling and deflecting the bullet and is why they are most commonly observed within 300 yards.

Barrel Twist & Bullet Stability

http://www.riflebarrels.com/articles/bullets_ballastics/bullet_imbalance_twist.htm

I also believe lead angle plays a role in this and is the reason dan lilja feels the way he does in this article.

http://www.riflebarrels.com/articles/bullets_ballastics/throat_angles.htm
 
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We could begin by agreeing that the term is EPICYCLIC (not Elliptical).
I'd love to see the source of the misconceptions so common here.. There must be one, because there is no way so many folks would share them on their own.

Read this article where Bryan tried his best to explore the notion, and could not support it:
Epicyclic Swerve

I'm pretty sure that the 'going to sleep' scenario originated to describe why long boat tail bullets could not COMPETE with short flat base bullets at 100yd events. That it was because longer BT bullets were disturbed more on release and took a while to damp out. This, causing detriment to 100yd grouping, so any advantage to higher BC bullets would not apply up close.

At longer ranges we do not expect precision in the 1s, and BC is more & more dominant to results with distance. Those short FB low BC bullets are very vulnerable to wind all the way to 1kyd, where hi BC BT bullets are less vulnerable. With hi BC bullets, we still can't shoot in the 1s at 1kyd(or any other distance), but we can reach for 1/2moa, which we couldn't do with low BC bullets.
So it was understood that advantages go to FB bullets up close, and BT bullets with distance.

But somehow this understanding(which passes tests) was extended(without basis) to explain other things. Somehow, the understanding that hi BC bullets DON"T SHOOT AS WELL up close, became hi BC bullets shoot BETTER with distance.. Then it apparently extended further, as it never made sense, so that hi BC bullets fly(like rockets) in a magic coning motion right past ugly 100yd grouping to produce better results further out. Maybe embellishments to campfire stories? I don't now, but I'm sure it would be amusing to know.

I'm trying to stomp out the campfire stories,, because I love beating my head against a wall I guess. But the rational lobe in my brain is now saying 'give it up'.
 
Mikecr said:
We could begin by agreeing that the term is EPICYCLIC (not Elliptical).
.
Click to expand...

Come on Mike, I meant to say elliptical. I know what the term is and I related it to the tip of the bullet in an elliptical motion just as Bryan stated "like putting a laser pointer on the tip shining on a wall" Also as indicated in the video. Maybe I should have said "circular" but it really does not matter as they are both a tip error pattern.

Anyway, like I said. "The problem" every time I have had it, was cured by simply moving the target out to 200 or 300 yards for load development. My personal "Cure" holds true to as far as I want to shoot, which I have tested to well over a mile. So what ever it is I can simply move my target and ignore it as long as she shoots 1/2 moa or better there and at a mile.

Best of luck on your quest.:)

Jeff
 
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