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Thread: Do bullets "go to sleep"?

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    Default Do bullets "go to sleep"?

    Here is an interesting collection of groups I recently shot with my 300 RUM. The first group is @ 100 yds and is .21" ctc. The other groups are @ 212, 326 and 427 yds fired on the same day but a different day than the first group. All the same load.

    What do you think? Just coincidence or does this load have different accuracy range nodes?







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    Not a ballistician (neither the keyboard variety nor a trained professional), but I've always wondered the same thing. I've seen it happen too often, but only with loooong bullets moving fast. My beloved 7mm RemMag is at the bottom of that scale, but it consistently shoots the same size group at 200 yards as at 100 yards. Whatever the explanations, I'll take that kind of performance.

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    Quote Originally Posted by BrownBear View Post
    Not a ballistician (neither the keyboard variety nor a trained professional), but I've always wondered the same thing. I've seen it happen too often, but only with loooong bullets moving fast. My beloved 7mm RemMag is at the bottom of that scale, but it consistently shoots the same size group at 200 yards as at 100 yards. Whatever the explanations, I'll take that kind of performance.
    Yup, the 230 Hybrids are loooong bullets and the RUM is pushing them right along @ 3100 fps. My experience with the VLD type bullets at high velocities has shown a number of loads that group better for MOA as they get down range to 300 or 400 yds.

    Interesting in this set of groups, is that the 100 yd group is tighter MOA than the 212 and 326 yd groups. Puzzling.... makes me wonder how much coincidence is involved.
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    Default Do bullets "go to sleep"?

    I think it's a nonsensical phrase invented by someone (not meaning you, MR) who was unwilling or unable to attempt to adequately describe what he really meant. Regardless, whether the phrase is taken literally, or figuratively, I would say the answer, in a word, is "no".
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    Well, way back a few years I had written on this forum extensively about just that and I used the term "go to sleep" to describe a bullet that settles to a its stabilized path. I do believe I was the first to use such a phrase. The "wobble" for lack of a better word, similar to a thrown football, is the result of dynamic forces acting on the bullet immediately after exit. This is referred to as yaw but is produced by such things as center of gravity and center of lift not being coincident, and what some refer to "over stabilization" though a true misnomer. It is simply the loss of the lateral and vertical stability of the confinement of the barrel. Meaning there is no support to hold the bullet straight as there was in the barrel and now it simply wobbles. These wobbles simple damp out because of the precessing from the gyroscopic stabilizing forces.

    So if it is a nonsensical phrase uttered by an idiot who could not explain what was happening, I'm your guy, I'm that idiot. Or it may have been that someone not wanting to put his audience to sleep used a more recognizable term and reference to a commonly viewed concept on TV every Sunday afternoon. Either way, I believe the phenomena does exist in the world of external ballistics and many others who are certified Ballistic Engineers believe the same.

    It's pretty cool thing to witness and I've demonstrated how the accuracy is better at some distance by shooting through paper targets stacked from 100 to 800 yards and shooting down hill slightly. Big paper targets at 100 yard intervals. Some cartridges have greater divergence in grouping from short to long range and I believe those with lower expansion ratios (large powder capacity and smaller bore) show a greater tendency toward this divergency. Possibly because of the high volume, excessive jet thrust of expanding exit gases exiting around the bullet. I also think I've shown how a good suppressor can reduce the exit yaw and reduce the short range groups. No conclusions but just some fun shoots. Just my thoughts on the subject.
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    Mr. Murphy, I didn't use the word "idiot", nor did I intend to imply such. I'm usually pretty literal in my definitions and understanding (at least I think so in my own mind). Without the phrase being defined, it seemed to me to be nonsensical (i.e meaningless, or not making sense (to me)). So, no offense intended, toward you or anyone else.

    I'll readily admit I'm sometimes a little slow to understand...but I want to. So, when you say "goes to sleep", are you simply meaning that the bullet becomes stable in flight, or are you intending to describe something more, and I'm just failing to understand?
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    First of all I would like to say those are great groups regardless! I would hate to be on the business end of that rifle with you shooting.
    I have a question if wondering about the grouping- would it not make sense to change the power of scope to be the same visual enhancement if doing a comparison? I ask this simply because using say a 12 power scope at 100 yds vs 300 yds will obviously have a lesser view and possibly hold point. What I mean here is using a 4 power at 100 yds, 8 power at 200 yds and 12 power at 300 yds.
    I may be completely off with my thinking......
    BEE

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    Are you asking if some bullets take longer to stabilize than others? If that is the case my answer is yes, speaking from my limited experience and considering what I know of harmonics, again limited knowledge.

    Or...

    It may have been as simple as a change in temp and/or humidity that went unoticed by you.

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    Quote Originally Posted by MontanaRifleman View Post
    Here is an interesting collection of groups I recently shot with my 300 RUM. The first group is @ 100 yds and is .21" ctc. The other groups are @ 212, 326 and 427 yds fired on the same day but a different day than the first group. All the same load.

    What do you think? Just coincidence or does this load have different accuracy range nodes?
    That question is way over my head, but the question I have is how consistent the pattern?

    Did you only shoot one 3 group, at each range, and on different days, with different conditions, etc.?

    I never trust JUST ONE 3 shot group. Not the way I shoot. One time I shoot well and next time, not.

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    Here is Brian Litz's demo of it:

    http://www.youtube.com/watch?v=4pF8W5liSRc

    Berger mentions the phenomenon in the VLD paragraph:

    http://www.bergerbullets.com/information/

    By the way, what ever the cause, VERY nice shooting.

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    I also believe that this does happen and I suspect that, nothing being perfect, the gas pressure at exit is not perfectly symetrical on the base of the bullet kicking it slightly into a wobble which goes away somewhere down range as the bullet stabilizes. I also think some of the groups being smaller at longer ranges can be blamed on scope parallax. If a scope is parallax adjusted to 200yds, it is quite possible to shoot better groups at 200 than 100.

    Murphy
    I am very interested in your results from shooting one group through several targets at different ranges. Did it ever happen where one group actually got physically smaller farther down range than at some closer range? I have wanted to try that for a while but don't have a place to get it done.

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    Sure they do! They find a balance where the spin drag becomes more constant and they drift-out at a decreasing rate from point when they ďgo to sleepĒ until they slow enough to become transonic and fight the shock wave.
     
    So, if we expect that drift-out rate to be less within that zone we would expect MOA numbers decrease there too because the angle number is linear (straight lines from muzzle to target) but the rate itís drifting out isnít linear any more than the rate itĎs dropping is. If you look at the spin drift numbers we all ignore on a drop chart you find that isnít linear ether. We expect a bullet to drop less 100 to 200 than it does between 300 and 400 so why should we expect it to flow a dead straight MOA line?
     
     
     
     
    But I think there is also a mental thing here we tend to discount too much. I think what happens is we rise to the challenge we think the shot presents us, we shoot better further out and more lazy closer in subconsciously . . . We tend to just phoning it in on the closer shots. Not picking on MR at all here because I think we all do it and not a thing wrong with those targets. Look at the 100 yard target then the others . . . all shot same gun, man, and ammo. Thereís some phoning it in on that 100 and much more all in the game thinking on the others donít you think?
     
    We know deep down as distance gets longer the shot must be harder and we step up our game accordingly. Itís the same as shooting at a critter at 30 yards that fills up the scope, we thing ďI canít miss thatĒ then we do miss it somehow. Well we told ourselves it was easy and went all lazy in the head, didnít give the easy shot due diligence. Opposite I think is true too ďdang that target is tiny way out thereĒ and we heighten our concentration, get more of the brain working on it.
     
    You hear these top shooters say ďthe center of the target is always the same sizeĒ right? I think that is why they are the top shooters. They are always telling themselves itís a tiny little very hard to hit target out there and concentrating hard on just a pinpoint every single shot. They are great shots because they have trained their subconscious that every shot is the most difficult shot and canít be phoned in.
     
    Anyway, right or wrong thatís what I think is going on.
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    Thats a very good psycho analogy of a shooter and valid explanation of another "phenomenon".
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    Quote Originally Posted by iofthetaiga View Post
    I think it's a nonsensical phrase invented by someone (not meaning you, MR) who was unwilling or unable to attempt to adequately describe what he really meant. Regardless, whether the phrase is taken literally, or figuratively, I would say the answer, in a word, is "no".
    Well, I'm not sure one way or the other. Seems to be evidence ofr and against in these groups. If it is true, then what's the deal with the 100 yd group? I believe the phrase is a metaphorical one.... and oh yeah... better do some more research before calling Murphy a nonsensical idot Jut kidding eh

    Quote Originally Posted by Murphy View Post
    Well, way back a few years I had written on this forum extensively about just that and I used the term "go to sleep" to describe a bullet that settles to a its stabilized path. I do believe I was the first to use such a phrase. The "wobble" for lack of a better word, similar to a thrown football, is the result of dynamic forces acting on the bullet immediately after exit. This is referred to as yaw but is produced by such things as center of gravity and center of lift not being coincident, and what some refer to "over stabilization" though a true misnomer. It is simply the loss of the lateral and vertical stability of the confinement of the barrel. Meaning there is no support to hold the bullet straight as there was in the barrel and now it simply wobbles. These wobbles simple damp out because of the precessing from the gyroscopic stabilizing forces.

    So if it is a nonsensical phrase uttered by an idiot who could not explain what was happening, I'm your guy, I'm that idiot. Or it may have been that someone not wanting to put his audience to sleep used a more recognizable term and reference to a commonly viewed concept on TV every Sunday afternoon. Either way, I believe the phenomena does exist in the world of external ballistics and many others who are certified Ballistic Engineers believe the same.

    It's pretty cool thing to witness and I've demonstrated how the accuracy is better at some distance by shooting through paper targets stacked from 100 to 800 yards and shooting down hill slightly. Big paper targets at 100 yard intervals. Some cartridges have greater divergence in grouping from short to long range and I believe those with lower expansion ratios (large powder capacity and smaller bore) show a greater tendency toward this divergency. Possibly because of the high volume, excessive jet thrust of expanding exit gases exiting around the bullet. I also think I've shown how a good suppressor can reduce the exit yaw and reduce the short range groups. No conclusions but just some fun shoots. Just my thoughts on the subject.
    Murphy, I do remember reading your opinion here on the subject. Not sure if it was in the same thread as you reference above. I tend to believe that the VLD type bullets do as you describe... for the most part... but how do you explain the 100 group?

    Quote Originally Posted by AKBEE View Post
    First of all I would like to say those are great groups regardless! I would hate to be on the business end of that rifle with you shooting.
    I have a question if wondering about the grouping- would it not make sense to change the power of scope to be the same visual enhancement if doing a comparison? I ask this simply because using say a 12 power scope at 100 yds vs 300 yds will obviously have a lesser view and possibly hold point. What I mean here is using a 4 power at 100 yds, 8 power at 200 yds and 12 power at 300 yds.
    I may be completely off with my thinking......
    BEE
    Thanks... I bet the majority of our members could do just as well or better and I wouldn't want to wager any serious $$$ against them.

    Interesting question indeed. I was using a 5.5-22 x 50 NF NXS on the 22x setting for all the groups. It has a very fine reticle and I was able to still barely bisect the 1" orange dot @ 427 yds with it. That said I was wondering myself, if that the relatively smaller bullseye @ 427yds made it easier to focus more on a "smaller" target? In other words, it was easier to eyeball the center of the bull because it was a smaller bull. But then again, the 100 yd group seems to dispel that idea?
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    Quote Originally Posted by .338WM View Post
    Are you asking if some bullets take longer to stabilize than others? If that is the case my answer is yes, speaking from my limited experience and considering what I know of harmonics, again limited knowledge.

    Or...

    It may have been as simple as a change in temp and/or humidity that went unoticed by you.
    I really don't think temp or humidity has much to do with it. The last 3 groups were fired about 15 - 20 min apart total time. I let the barrel cool between each shot.

    My thought is that some bullets do exhibit the process that Murphy described and Litz's simulation illustrates. I think a lot of it has to do with the physical characteristics of the bullet and maybe also the characteristics of a particular load and barrel as to the degree of the phenomena... but not totally sure. So that is the question.

    Quote Originally Posted by Smitty of the North View Post
    That question is way over my head, but the question I have is how consistent the pattern?

    Did you only shoot one 3 group, at each range, and on different days, with different conditions, etc.?

    I never trust JUST ONE 3 shot group. Not the way I shoot. One time I shoot well and next time, not.

    Smitty of the North
    Smitty, I am down to 4 bullets and about a dozen tattered peices of brass. I have a friend near by in Helena that I might meet up with to do some LR drop validation tomorrow (with another rifle... 6-284) that has a spare box of bullets for me but I have to wait on brass. I am going to get some of Shawn Carlock's 338 EDGE brass made by Bertram and neck it down. Much better quality and much better durability than the RP junk that wont hold primers after 4 or 5 firings. It was the first set of groups after picking a load from load development. I'm going to run this test again once i can load some more rounds.

    Sooo... consistency is a question at this point. I think it's fair to say the rifle and load are capable of .2 - .5 MOA accuracy based on the 4 separate groups. The question is will the pattern hold up next time around or will the accuracy imporve @ 212 and 326 and fall of @ 100 and 427, or some combo thereof? In other words, is this load randomly a .5 MOA shooter overall and are the .2 MOA groups random flukes of the better part of the whole population?

    Quote Originally Posted by GD Yankee View Post
    Here is Brian Litz's demo of it:

    http://www.youtube.com/watch?v=4pF8W5liSRc

    Berger mentions the phenomenon in the VLD paragraph:

    http://www.bergerbullets.com/information/

    By the way, what ever the cause, VERY nice shooting.
    If you read Litz's article on this, IRRC, I think he states that in his opinion, he has seen no significant evidence of this phenomena in his experience. I will have to try and find the article.

    And thanks
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    Did you only shoot one 3 group, at each range, and on different days, with different conditions, etc.?

    I never trust JUST ONE 3 shot group. Not the way I shoot. One time I shoot well and next time, not.

    Smitty of the North
    Oh yeah... the first group was shot about 2 or 3 days prior the the last 3 which were shot back to back letting the barrel cool between shots. I actually shot the 326 yd group before shooting the 212 yd because I thought I was on the 212 yd target
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    Quote Originally Posted by MontanaRifleman View Post
    427 yards???....holy smokes!!!....No matter what the answer is, that's some da*n fine shootin' right there...!!!
    Sheep hunting...... the pain goes away, but the stupidity remains...!!!

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    ^^^^^ What he said!^^^^^
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    Quote Originally Posted by rbuck351 View Post
    I also believe that this does happen and I suspect that, nothing being perfect, the gas pressure at exit is not perfectly symetrical on the base of the bullet kicking it slightly into a wobble which goes away somewhere down range as the bullet stabilizes. I also think some of the groups being smaller at longer ranges can be blamed on scope parallax. If a scope is parallax adjusted to 200yds, it is quite possible to shoot better groups at 200 than 100.

    Murphy
    I am very interested in your results from shooting one group through several targets at different ranges. Did it ever happen where one group actually got physically smaller farther down range than at some closer range? I have wanted to try that for a while but don't have a place to get it done.
    Interesting theory on the gas pressure at exit. Parallax is not a factor in this case, the NXS has parallax adjustment.


    Quote Originally Posted by ADfields View Post
    Sure they do! They find a balance where the spin drag becomes more constant and they drift-out at a decreasing rate from point when they ďgo to sleepĒ until they slow enough to become transonic and fight the shock wave.
     
    So, if we expect that drift-out rate to be less within that zone we would expect MOA numbers decrease there too because the angle number is linear (straight lines from muzzle to target) but the rate itís drifting out isnít linear any more than the rate itĎs dropping is. If you look at the spin drift numbers we all ignore on a drop chart you find that isnít linear ether. We expect a bullet to drop less 100 to 200 than it does between 300 and 400 so why should we expect it to flow a dead straight MOA line?
     
     
     
     
    But I think there is also a mental thing here we tend to discount too much. I think what happens is we rise to the challenge we think the shot presents us, we shoot better further out and more lazy closer in subconsciously . . . We tend to just phoning it in on the closer shots. Not picking on MR at all here because I think we all do it and not a thing wrong with those targets. Look at the 100 yard target then the others . . . all shot same gun, man, and ammo. Thereís some phoning it in on that 100 and much more all in the game thinking on the others donít you think?
     
    We know deep down as distance gets longer the shot must be harder and we step up our game accordingly. Itís the same as shooting at a critter at 30 yards that fills up the scope, we thing ďI canít miss thatĒ then we do miss it somehow. Well we told ourselves it was easy and went all lazy in the head, didnít give the easy shot due diligence. Opposite I think is true too ďdang that target is tiny way out thereĒ and we heighten our concentration, get more of the brain working on it.
     
    You hear these top shooters say ďthe center of the target is always the same sizeĒ right? I think that is why they are the top shooters. They are always telling themselves itís a tiny little very hard to hit target out there and concentrating hard on just a pinpoint every single shot. They are great shots because they have trained their subconscious that every shot is the most difficult shot and canít be phoned in.
     
    Anyway, right or wrong thatís what I think is going on.
    Interesting theory and psycho analysis I subscribe to the idea of a higher level of concentration when the shot is more challenging. I catch myself getting lazy sometimes as well. In the case of these groups cocnetration was about the same. I may have a little more on the 427 yd target, but not nearly enough to account for the difference between it and the 21 and 326 yd groups. BTW, I was shooting off a front Caldwell Bag like this one

    http://www.midwayusa.com/product/886...g-nylon-filled

    and a rear bag. I used pressure on the rear bag with my left hand to adjust POA. I figure the shooter (me) could easily account for up to .1 MOA of error. Can be very challenging to hold those crosshairs dead still. So I figure if I shoot a .2 MOA group, the rifle/load might be capable of .1 Or... maybe I just held a little better on those tighter groups, but not more than .1 MOA better.
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    Quote Originally Posted by MontanaRifleman View Post
    I believe the phrase is a metaphorical one....
    Well, yeah, that was apparent to even my autistic way of thinking. But the initial question it raised in my mind was; a metaphor for what, exactly? And now my understanding is that it's a metaphor for the point at which a given bullet in flight exhibits stability; is that correct?

    I think, what would be really cool, rather than shooting through many successive targets, would be to set up a long range lab wherein we could photograph a bullet, against a background reference grid, along it's entire flight path for perhaps a thousand yards, and computer analyze it's motion through it's entire flight. The technology exists to easily do so; we've been doing it for years over short distances. It would just be a matter of money to set up a long range lab...
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