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Bullet goes to sleep mode

jajajaja
I see that the same old argument is still going on even though it was answered more than a year ago.
Just admit you cannot comprehend the physics. Because of that you can never be satisfied by any answer.

When you say something like, "No you are wrong" it turns folks off and shuts down meaningful technical discussion from folks that have something significant to offer on the subject. I think it is better to just give your technical explanation on your opinion of the subject. This subject is highly technical and simply saying that you have seen it or that a friend has seen it without adequate technical justification is not helpful. Fortunately there are some good technically sound inputs on this interesting topic on this thread.[/QUOTE]
 
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jlow said:
Brian actually worked out a system to get precision data from the same bullet at both distances. Basically the bullet is fired at a thin sheet of paper at 100 yards and after it goes through the paper it also impact at a regular target an extended distance. By firing a number of rounds this way, he can get a sense of grouping for the same bullets at both distances.
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Dr. F. W. Mann did the same thing first over a century ago. Read his book "The Bullet's Flight from Powder to Target." Brian Litz just used longer ranges, Dr. Mann (a surgeon) did his tests up to 100 yards.
 
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Bart, Barrel tuners have nothing to do with stabilizing the bullet. They can be useful to tune the harmonics of the barrel. Are you implying that the stability of the bullet is a non-issue for the perceived problem of a bullet not stabilizing until after traveling a certain distance down range?

If so, I happen to agree. I am well aware that a barrel stabilizer can make up for barrel harmonics at a given range but only at the expense of group size at other ranges. I am also a believer in a bullet being as stable as it can be as it leaves the muzzle. (that time in flight does nothing to further stabilize the bullet)

The original post was a question of a bullet being unstable as it came out of the barrel and then "calmed down and went to sleep" at some range in its flight. Your points are well taken but have nothing to do with bullet stability which is what my post was about.
 
SheepDog said:
I typically shoot larger groups at 25 yards than at 50 with my 22LR. I did this the other day using a 1/2" bull and then I decided that at 25 yards I need a smaller target to aim at. The groups at 25 yards shrunk to about a third of what they were before when I used a 1/4" bull.
It might be the natural tendency to focus harder on the more distant targets. That would result in smaller groups at more distant range.

It's not that I believe that a bullet can become more stable as it travels down range, it's just that no one has ever explained how it can happen without defying the laws of physics. I have an open mind but I still filter what goes in.
Click to expand...

Now this guy has something.

Those who shoot smaller MOA groups at longer range are aiming smaller at the longer range.

This makes more sense to me then the bullet's path changes after a few.hundred yrds.
 
Gstaylorg,
The stability of the bullet is determined by its rate of spin (# of turns per foot of travel) compared to its length. The velocity has little to do with its stability as can be noted as the bullet slows to the transonic velocity range. In that velocity range the rate of spin has changed a lot less than its velocity but the center of pressure is changing relative to its center of gravity forcing the bullet into a struggle to maintain pointing into the line of flight. A bullet that is too long to stabilize in a 1 in 12 twist will not stabilize in that twist no matter how fast you launch it.
Now MAYBE, if you can get it going close to the speed of light its mass will increase and its length will decrease enough to stabilize it but that is relativistic physics and really doesn't apply.
 
If bullets "went to sleep" and thereby shrunk in group size, why wouldn't they all do it every time? Should be *really* easy to show how this works.

How does this work? I keep hearing how simple it is to explain, but I have yet to hear a simple explanation.
 
SheepDog said:
The stability of the bullet is determined by its rate of spin (# of turns per foot of travel)
Click to expand...
No, that's not the correct rate of spin. Stability requirements are expressed in displacement per turn(ex. 8" per turn). Displacement includes air density, or distance through local density.
Travel drops off faster than spin, so effective displacement per turn drops, and this is way more dominant in stability than drag changes with velocity. So gyroscopic stability normally goes up downrange. Dynamic stability is another matter.

But this external ballistic attribute cannot cause decreasing groups with distance. As mentioned before, such a possibility would include an external and intelligent force to will it back to POA..
IMO, better aiming passes the most tests.
 
I'm
Richard Coody said:
Those who shoot smaller MOA groups at longer range are aiming smaller at the longer range.
Click to expand...
Myth #22 for competitive rifle shooting.

Having been one, shot with many, won matches with and oft times discussed that myth with the top ranked competitors, we all agree our aiming area on target subtends the same angle from 50 to 1000 yards. Our bodies bounce around the same from pulse beats expanding and contracting our muscles connected to the bones supporting our rifles. They behave the same way at all target ranges. We try to get all shots off called inside that area. Plots of called shots look identical to shot hole groups; most in the inner third of the diameter, some in the next third and a few in the outside third. Its size varies a little across all because our bodies do.

Hold, aim or wobble (your choice) areas are typically 1/2 to 2/3 MOA, the point of aim goes in sort of an oval shaped figure 8 pattern a little taller than wide.
 
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SheepDog said:
Gstaylorg,
The stability of the bullet is determined by its rate of spin (# of turns per foot of travel) compared to its length. The velocity has little to do with its stability as can be noted as the bullet slows to the transonic velocity range. In that velocity range the rate of spin has changed a lot less than its velocity but the center of pressure is changing relative to its center of gravity forcing the bullet into a struggle to maintain pointing into the line of flight. A bullet that is too long to stabilize in a 1 in 12 twist will not stabilize in that twist no matter how fast you launch it.
Now MAYBE, if you can get it going close to the speed of light its mass will increase and its length will decrease enough to stabilize it but that is relativistic physics and really doesn't apply.
Click to expand...

As noted by mikecr, bullet gyroscopic stability most definitely does increase with distance. The caveat to that is that the bullet can't be completely unstable immediately as it exits the bore or it will tumble before it has traveled enough distance to allow the gyroscopic stability to increase sufficiently to overcome the insufficient twist rate. However, this has been demonstrated conclusively using barrels of marginal twist rate, but not so slow that the bullet tumbles immediately. Dynamic stability is a different story, as is yaw/pitch that occurs as the bullet exits the bore and has proposed as the mechanism to explain bullets "going to sleep". The magnitude of the effect (at least in 6DOF computer simulation) was quite small, however, and not sufficient to explain the decrease in group size over distance described by those claiming their groups actually became smaller.

As Damon noted, the claim of consistently smaller groups over distance should be quite simple to demonstrate, even if somewhat more challenging to explain. The fact that such evidence is lacking IMO is strong support that it is largely anecdotal and doesn't hold up to more rigorous scrutiny and testing. Lack of evidence is never "proof" that something doesn't exist or cannot occur, but this idea has been around for a while. If this phenomena was a common occurrence, I'd expect we'd already have plenty of solid evidence to support it.
 
SheepDog said:
Are you implying that the stability of the bullet is a non-issue for the perceived problem of a bullet not stabilizing until after traveling a certain distance down range?t)
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No.

But yes, barrels tuners work best at one range. I've seen smallbore ones set different for 100 yards than 50.

I don't think all bullets are perfectly stabilized as they clear the muzzle.

Sierra Bullets chronographed bullets entering a close and far range band inside 100 yards, got entry velocity into and time of flights across them for each bullet, then calculated BC for each bullet in each range band. All bullets had lower and greater spreads of BC's in the close range band. BC's in the far range band had little higher BC's with lower spreads. Proof they stabilized better as they got closer to 100 yards. Their 100-yard test groups in the .1 to .2 inch size is the icing on this ballistic cake. Their best 30 caliber 168 to 190 grain match bullets shot under .2"/MOA at 100 yards, sometimes under .1.

Muzzle blast around bullet heels is not always the same from shot to shot. Better with boattail than flat base bullets of longer lengths. That tips bullet bases as they exit so it takes time to get them spinning true.

Sierra's first ballistic tech told me they noticed some lots of 30 caliber 165 grain hollow point hunting bullets shot more accurate than 180 grain FMJBT match bullets. Precise measurement of their heels showed the 165 BTHP had smaller spread. That convinced them to make the 30 caliber match bullet contracted in 1957 by the US Army international rifle team for 300 meter free rifle events a hollow point one. Then they sold it at retail in 1958 as the 168-gr. International BTHP. Their first 30 caliber hollow point match bullet.
 
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Bart B. said:
I'm
Myth #22 for competitive rifle shooting.

Having been one, shot with many, won matches with and oft times discussed that myth with the top ranked competitors, we all agree our aiming area on target subtends the same angle from 50 to 1000 yards. Our bodies bounce around the same from pulse beats expanding and contracting our muscles connected to the bones supporting our rifles. They behave the same way at all target ranges. We try to get all shots off called inside that area. Plots of called shots look identical to shot hole groups; most in the inner third of the diameter, some in the next third and a few in the outside third. Its size varies a little across all because our bodies do.

Hold, aim or wobble (your choice) areas are typically 1/2 to 2/3 MOA, the point of aim goes in sort of an oval shaped figure 8 pattern a little taller than wide.
Click to expand...

If i have this right you are of the school if you shoot half MOA at 100 you can expect to shoot half.MOA at 1000

Now i can see, disregarding wind and mirage, with a heavy bench gun and a high power scope shooting free recoil that it would.be possible to aim smaller at distance.
If what i am saying makes sense.
 
Richard Coody said:
Now this guy has something.

Those who shoot smaller MOA groups at longer range are aiming smaller at the longer range.

This makes more sense to me then the bullet's path changes after a few.hundred yrds.
Click to expand...
What is the measurement of a half MOA at 100 yards vs 1000? You assume (because Litz told you to) that a bullet is held to some mathematical measure through it's flight.. I would think as a Shooter/Reloader you could see just the environmental differences from shot to shot..

Just think of the force from being fired and differences of flight from muzzle to distance.. Bullets are being thrusted violently then go into free flight. I completely understand that a bullet can "go to sleep"...

You know, if someone can sell books he has to stand behind his "theory"..

Ray
 
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damoncali said:
If bullets "went to sleep" and thereby shrunk in group size, why wouldn't they all do it every time? Should be *really* easy to show how this works.

How does this work? I keep hearing how simple it is to explain, but I have yet to hear a simple explanation.
Click to expand...

Simple, bullets don't travel in minutes of angle..

Ray
 
Raythemanroe said:
What is the measurement of a half MOA at 100 yards vs 1000? You assume (because Litz told you to) that a bullet is held to some mathematical measure through it's flight.. I would think as a Shooter/Reloader you could see just the environmental differences from shot to shot..

Just think of the force from being fired and differences of flight from muzzle to distance.. Bullets are being thrusted violently the go into free flight. I completely understand that a bullet can "go to sleep"...

You know, if someone can sell books he has to stand behind his "theory"..

Ray
Click to expand...

It's not his theory. It's the cumulative, repeatedly tested, and verified experience of western civilization dating back to before Isaac Newton. There's not a serious ballistics engineer alive who believes that bullets "go to sleep" except in the way that Bryan describes. If you believe otherwise, you are running counter to the countless thousands of people who have studied physics and engineering and the methods used to create supersonic aircraft, spacecraft, guided missiles, and yes, match grade bullets capable of holding less than than a quarter minute at 1000 yards.
 
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