I might be getting off track here but this interesting.
All arrows wobble/yaw when released. All of them. The quicker they stabilize or settle down, and if they stabilize, has a great impact on accuracy. Watch these videos, they will AMAZE you. I still remember the sense of awe I experienced when I was about 10 and saw this video for the first time. It still amazes me now.
Now the key point here is that an arrow and bullet experiences wobble along an axis that follows the trajectory, and does not create a curve ball or arc across the axis (as this and other videos show). So no you can't group an inch at 300 yards and 3 inches at 100 yards.
By the way folks... call me Kyle. Sorry about the whole Heikki thing, I just added Kyle to my signature. Hope everybody has a good day... It's raining here
Thanks for the videos Kyle.
I tend to agree with you.
And yes we're getting off track but the cans been opened and the worms are free.
WW
Sorry buddy. I took a guess at sleeping bullet showing returns and your right. Diddley up to page 15 where even I gave up I'll make amends.
For the folks who believe heres some ammo. For the folks who don't read on and perhaps be swayed. Simply interested with no opinion,continue at your own risk.
Search for
Epicyclic Swerve
Aerodynamic Jump
Bullet Yaw
Personally I believe these things are real but see no way they can create better moa returns at longer range.
I also never row my boat far from shore for fear of falling off the world.
Enjoy your studies folks and don't stay up to late.
In the mid 1990's when I was experimenting with 6-284's and 25-06's for long range varmint shooting I experienced this and read articles about it. The one article and follow up letters and comments that I remember best was in Precision Shooting Mag.
Let's stir the pot a little more. Last year many of us wrote on this forum about 32 gr SBK's that tumbled at high velocity(usually at 4100 fps or more). My own experience was at 4170 as tested by a chrony and an oehler. These bullets did not come apart, they simply had extreme yaw and started to tumble. I had some partial and full keyholes in paper targets at 100 yards opening groups to 3-4 inches.
Why would it be hard to believe that a bullet with nearly, but not quite, that much yaw would result in bad 100 groups yet would settle in to good rotation at say 125-150 yards and have better groups from that point out to loss of stability.
I'm no scientist--but I am a shooter with a lot of experience and I believe what I have seen more than what I have been told. This I have seen!
Feel free to argue amongst yourselves as this will be my last word on this subject.
Let's stir the pot a little more. Last year many of us wrote on this forum about 32 gr SBK's that tumbled at high velocity(usually at 4100 fps or more). My own experience was at 4170 as tested by a chrony and an oehler. These bullets did not come apart, they simply had extreme yaw and started to tumble. I had some partial and full keyholes in paper targets at 100 yards opening groups to 3-4 inches.
Why would it be hard to believe that a bullet with nearly, but not quite, that much yaw would result in bad 100 groups yet would settle in to good rotation at say 125-150 yards and have better groups from that point out to loss of stability.
Hotshot-- I hope you don't mind me using your words & hiliting a few. My thoughts FWTAW are that 4100fps or higher was too much velocity for them in your particular rig & when they lost velocity after another 50yds or so they settled in to the proper rotation until they hit the other end of too little velocity. This is just the way I look at this subject too. After all,, a hard spun top will sometimes wobble for a second or three then settle into a nice tight spin also. Now I'm telling how old I really am. I used to play with tops!!
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Wow, I just started reloading last year and had not heard of sleeping bullets. My question was more about the process you use to develop the most accurate load for your rifle at say 400 yards. With the variables shooting longer ranges I thought I was missing the whole accuracy thing by not first shooting groups into the .1 or .2 at 100 yards (or atleast fun trying) and then test them at longer ranges. I loaded several different loads last year but did a poor job of using a standardized process of comparing different bullet and powder combos. I had a box full of targets shot at different yards.
Anyways my son and I had a lot of fun shooting last year and are looking forward to this year.
O.K. I just have to pass this along.
This is really wierd... all this talk of "sleeping bullets" lately and what do you know, today I happened upon some credible mention of it. Today I got the new edition of Precision Shooting, June 2008, Vol.56, No.2. In it there is an eleven page article written by James A. Boatright titled "Understanding the Bullet's Flight Through Crosswinds - Part I". It is much to complex for me to summarize, but I suggest reading the entire article for those interested. In no way am I affiliated with Precision Shooting, but here goes my sales pitch. First off I love them, they are a great monthly magazines at only $3.95 each! In this issue there is a great article on primers that shows primers being detonated and images of the flame lenght from each. Anyways... I'm done with that. Back to the "sleeping bullets".
As mentioned, there is simply too much info for me to summarize, so I'll give you the exact excerpt that directly mentions "sleeping bullets".
NOTE: All text styles such as italics and bolds are those of the authors.
Oscilation is a fast-mode nodding or bobbling motion of the bullet's spin axis that resembles gyroscopic nutation and is normally due to launch disturbances caused by: 1) A worn, distorted or dinged muzzel crown, 2) A damaged or un-square bullet base, 3) Imperfect bullet obturation, 4) A crosswind at the muzzel, 5) In-bore yaw, or by 6) A static or dynamic imbalance of the bullet itself.
The initial angular size of the bullet's slow-mode "coning motion" (i.e., its cone angle a) begins right after launch with whatever size oscillation motion the bullet might have been given initially. The fast-mode oscillation amplitude subsequntly damps to an imperceptible level fairly rapidly (wth this bullet, as with probably all match bullets) within the first few thousands of calibers of forward travel (i.e., within the first couple of slow-mode coning cycles). This damping out of the fast-mode oscillation of the bullet is probably what some benchrest competitors refer to as the bullets "going to sleep."
I think some shooters believe that bullets "go to sleep" much farther down range. The process you quoted is a normal transition for most bullets exiting the barrel. As a bullet travels down the bore it must rotate around its center of form because the barrel keeps the bullet confined to that rotation. Immediately upon being free of the bore the bullet will start rotating around its center of gravity. I think that is what is being described in your quote. This transition happens almost immediately as the bullet is free of the bore. The other factors such as a dinged muzzle or un-square bullet base may further upset the rotation of the bullet as it exits the muzzle but, the bullet should recover from this type of deflection also almost immediately.
The "sleeping bullet theory" has been used as an explaination by those who believe that some bullets will group loosely at, say, 100 yards and then somehow miraculously group tighter farther down range.
I'm sure there are many more opinions to follow. This is like opening a can of worms.
As Skipper said bullets rotate around the center of gravity upon exit of the barrel. A number of factors effect how much the bullet will actually get from its center of gravity. The bullet does not always increase this distance from its original center of gravity proportionally to the distance it has traveled. One of the major factors of the extent of this travel is the barrels position in its "wobble" (the barrel moving up/down during firing) as the bullet leaves the barrel. One way to change this relationship is to vary the powder charge and therefore changing the velocity. My point is that just because a bullet/rifle combo shoots a certain moa at 100yds does not mean it will be the same at 600yds. One example I saw recently was a review on the Savage F/TR. The worst bullet's group at 100yds was the best group at 600yds. If I were you I would definitely load for the desired distance.
I'm not really on either side of this, but I found something yesterday that makes me lean toward the sleeping bullets. I have a load that shoots in the low .3s at 100 yards, but at 200 yards it shot around 1.5"-2". I decreased the powder charge by .1 gr. and it started shooting about .75"-1" average at 200 yards for 5 and 4 shots averaged a little over .5". At 100 yards it averaged 1" with the smallest being .75"
Bomb Squad: If you see me running, try and keep up
Gee.... I'm surprised to see the "sleeping bullet theory" topic being discussed here.
Several years ago I threw it out as a possible explanation that had been floating around in shooting circles for years as to why the phenomena of a group at 200 yards consistently being better than a 100 yard group fired with the same load and bullet. I never stated that I believed the theory but that it was at least a plausible attempt to explain the 100/200 yard phenomenon that many shooters - including BR shooters - had experienced.
The net result was I was declared to be an idiot by several posters who could not prove one way or the other that it had any meaning. As I explained, neither could I, but it was a theory that had been floating around for years. I was even told that one prominent poster here even related later on that he and others had "driven" me from the forum because I mentioned it and that it was a stupid idea.
For the record - its recent appearance in Precision Shooting is not the first time it has been discussed there. And also for the record, no posters drove me from the forum at that time.... I just chose at that time to not argue with folks who believed they were too intelligent to even consider an idea they could not explain one way or the other - right or wrong... so I took a vacation...
As for the idea that a bullet spins around its center of gravity as soon as it leaves the muzzle; for the most part that is correct. However there is also actual photographic evidence of what is referred to as "conical dispersion" that occurs after a bullet exits a muzzle. Conical dispersion occurs immediately after a spinning bullet leaves a muzzle and the heavier rear of the bullet tries to change places with the front of the bullet which has considerably less mass. Since the bullet is spinning, the path of the rear end of the bullet takes on a conical dispersion from the center of the bullet's path and possibly affects bullet accuracy. Eventually the conical dispersion is overcome by bullet spin with a stable bullet, and the dispersion diminishes further downrange - again seen photographically. As I stated then, whether or not this is a part of the "sleeping bullet theory" as some apply it, and whether it answers the different accuracy levels at different distances is beyond me. But, conical dispersion exists... And some bullet designs exhibit it more than others do.
In a practical application, conical dispersion is one reason that a lot of pistol shooters have used full wad cutter bullets for years. They exhibit very little conical dispersion since the front of the bullet weights the same in equal cross sections as does the rear of the bullet. Hence, good consistent accuracy results at varying pistol bullet ranges if the bullet is spinning at a proper rate.
So.... As I stated several times back then, I have no idea if the "sleeping bullet theorists" are right or wrong. I just know I'm personally not smart enough to declare them to be idiots simply because I don't have a logical answer to disprove what they are saying and have been saying for years.
Good to hear from you BCB. I'd just like to say, in a complimentary way, that BS doesn't get by this man without getting called.
I don't know if any of you have respect for Robert Rinker author of Understanding Firearm Ballistics. Personally, I find his writing very dry and hard to follow, but he sure knows math formulas and he can talk the science of flying bullets.
His article in #65 issue of Varmint Hunter goes into depth about what happens to bullets as they accellerate and spin down a barrel, then exit that barrel and start their return to earth.
Initial wobble, which he terms nutation, is a natural gyroscopic result of fast accelleration and spin of the bullet going from zero to fast in a big hurry. Nutation creates a helical flight that is a small fraction of an inch and dies out quickly(50 yards or less typically).
There are, however, gyroscopic results from yaw and precession that create helical flight patterns that can last up to 200 yards at which point stability and air resistance tend to take charge and put the bullet into a consistant flight pattern. Yaw persists in some extent simply because the bullet is spinning around it's center line and the trajectory is pulling the bullet at a downward curve.
Since any load fired in a given barrel will always have uneven forces upon the bullet, there will always be yaw and precession to contend with and some bullets will not go to sleep untill they near 200 yards. It is possible and it does happen.
I'll make amends.
Hold 'em & Squeeze 'em
