Bullet goes to sleep mode

[DHD]

My eye balls hurt. There have been some really good/funny replies on this thread though. I'm going to get another cup of coffee and about 6 Excedrin's and hope they quit yawing......

 

[Homerange]

The known phenomenon is the reduced motion of the bullet tip wobbling through smaller pitch and yaw angles as the bullet flies down range. This "going to sleep" is not the same as the oft-claimed shrinking of MOA of group sizes (dispersion) as a bullet flies downrange.

Why is it not?
When the yaw is more extreme than what is apparently normal (well balanced load) won't it create greater group dispersion?

The theory related to shrinking dispersion actually asserts that the whole bullet is flying in something of a corkscrew or helical motion, and that the diameter of the helix gets smaller with increasing range such that groups at 200 yards and out have a smaller angular dispersion (MOA) than groups closer.

I ask just what sets the helical motion off, is it not pitch and yaw?
What follows is how does the pitch and yaw originate?

 

[Raythemanroe]

I am suggesting that bullets although out performed by others at pointblank ranges can run through conditions better then some.. which would give the appearance of somehow defying logic but in reality is just less effected by conditions.. Bryan Litz, wouldn't this be the whole idea of high BC bullets, to out perform others at distance?

Ray

 

[Joe Salt]

I've watched videos of bullets coming out of a rifle and from what I could gather they do wobble at first, but like an arrow they straighten out. It has to do with force on the object being pushed. If you had 60 thousand pounds of force on your butt are you going to stay straight. I've also seen vapor trails that were wider and looked like they were cork screwing they didn't shoot so well if I'm remembering right. It looked wide, not small like most.

Joe Salt

 

[dkhunt14]

I have always shot better in moa at distance, than at 100yds, with every gun I've had. But of course, it's not my guns.
My theory, can't prove it:
I think it's parallax. It seems much easier for me to identify the exact point of 'parallax removed', on a paper target, further out. At 100yds, while I get only somewhat close to this parallax removed point, my brain adjusts enough to see the target solidly resolved just as it can for a 'slightly out of focus' condition at 100yds.
But this isn't really good enough.
Any bit out of focus at 500yds is very obvious, and unacceptable. My brain cannot even try to compensate for it. So I can precisely remove parallax at 500yds.
Well, at least it seems this way to me and my corrected vision.

If it is parallax, what about the rail guns or heavy guns that don't move or get adjusted. That would take parallax or aiming out of the picture.

Take a top that is spinning and wobbling and touch it and it goes nuts and takes far less force to move it. Take the same top that is spinning straight and true and it takes constant force and more of it to move it. I believe the same thing happens with wind and forces moving a bullet. I have seen it many times with a heavy gun that weighs 80 pounds and tracks good enough that adjustment doesn't need made. Like Joe, I have seen bullets corkscrewing on the way to target at 1000. When that happens, it is not near as small as the gun will shoot and you will have wild fliers. Matt

 

[Raythemanroe]

I agree Matt, a Hummer isn't defying conditions, it's stability starting from muzzle allowing less unwanted effect? I say yes..

I believe some accuracy can be given up in exchange for down range performance.. The WSM probably will never compete in 100-200y aggs and don't say it is just the recoil..

Ray

 

[Joe Salt]

The other thing I forgot to mention was if your rifle doesn't like bullet A but likes bullet B what do you think is happening to bullet A ?

Joe Salt

 

[Berger.Fan222]

Why is it not?
When the yaw is more extreme than what is apparently normal (well balanced load) won't it create greater group dispersion?

I ask just what sets the helical motion off, is it not pitch and yaw?
What follows is how does the pitch and yaw originate?

Think about a football. Whether a tight spiral or a wobble, the center of mass flies in a normal trajectory without some weird helical path.

The wobble increases drag but it does not create a weird helical path that is less accurate at close ranges and then becomes accurate when the wobble damps out.

 

[Homerange]

Think about a football. Whether a tight spiral or a wobble, the center of mass flies in a normal trajectory without some weird helical path.

The wobble increases drag but it does not create a weird helical path that is less accurate at close ranges and then becomes accurate when the wobble damps out.

Sorry that doesn't do it for me. The mechanics of bullet flight are much more complex.

The other thing I forgot to mention was if your rifle doesn't like bullet A but likes bullet B what do you think is happening to bullet A ?

This. ^^^^^^^

 

[MattPeetz]

Rudamentary drawing but how can a bullet turn directions on its own to have a non linear path?
Its not possible.
If that was possible no ballistic calculator would be able to predict bullet flight to hit at extended ranges.

 

[chkunz]

Rudamentary drawing but how can a bullet turn directions on its own to have a non linear path?
Its not possible.
If that was possible no ballistic calculator would be able to predict bullet flight to hit at extended ranges.

View attachment 979834

Exactly! And even if it were possible why would they all choose to turn inward and make the group smaller rather than turn outward and make the group larger. Refer back to my reply #15 above.

 

[seandradamus]

Exactly what I was talking about , you show all shots emanating from 1 point
Now with even a small amount of parallax they may be flying closer to parallel.
The barrel and gun moves every shot it is not a perfect fixed point.
Therefore a 1" group at 100 could be 1" at 200 or twice as good.

 

[MattPeetz]

Thats parrallax and has nothing to do with a bullet changing its course of direction on its own.

 

[Joe Salt]

Guys depending on the wind velocity, that is all that is changing the path of the bullet as long as the wind is steady the bullet should stay in the same place on the target. If you get a pick up or a let up it goes left or right or sometimes high. That's why we pick the condition.

Joe Salt

 

[Homerange]

So presuming that NO external parameters affect bullet flight (of course there are), that flight may be influenced by unmeasurable factors that will affect the flight. Reloaders need only be aware of these. They MIGHT be twist rate (to little, too much), velocity and/or an unsuitable bullet. A combination of these things (and others) might make the flight unstable resulting in yaw and pitch which might then lead to an elliptical path (extreme) all of which may be dampened during flight that results in better groups than might be seen at close range.

That's my interpretation of the published data and this threads OT discussion.
I know some here don't subscribe to this POV, however I'd gladly listen to comments on my above understanding of unstable bullet flight.

We're here to learn aren't we?

 

[Joe Salt]

So presuming that NO external parameters affect bullet flight (of course there are), that flight may be influenced by unmeasurable factors that will affect the flight. Reloaders need only be aware of these. They MIGHT be twist rate (to little, too much), velocity and/or an unsuitable bullet. A combination of these things (and others) might make the flight unstable resulting in yaw and pitch which might then lead to an elliptical path (extreme) all of which may be dampened during flight that results in better groups than might be seen at close range.

Yes you are correct we all strive for that perfect rifle, but some may never find it. Sometimes you will get a good combination barrel, bullet. But most have to make do with what there dealt. So the next question is can I improve this with reloading or with my wind reading. I myself have never had a rifle that shoots really tight groups at 100 yards that will shoot the kind of groups I would expect at 1000 yards. Sorry but no magic bullet.

Joe Salt

 

[ashiha]

Could it have to do with twist rate decay as the bullet travels?

A bullet spinning right out of the barrel obviously spins much faster than it does at 1000 yards. Could it be that those experiencing this might have very slightly too much spin which reduces at further ranges? Is there even such a thing as too much spin?

Just throwing another thing into the hat.

 

[Raythemanroe]

Rudamentary drawing but how can a bullet turn directions on its own to have a non linear path?
Its not possible.
If that was possible no ballistic calculator would be able to predict bullet flight to hit at extended ranges.

View attachment 979834

1" at a 100 is still 1" at 1000, If we are talking straight lines.. Does your "MOA" line account for barrel canting or bullet drop? Would you presume laser like MOA lines are a constant and reworld ballistics do not apply?

Mathematical models for calculating the effects of drag or air resistance are quite complex and often unreliable beyond about 500 meters, so the most reliable method of establishing trajectories is still by empirical measurement.

Question, Has anyone measured a perfectly round group? Anyone measured a perfectly centered bore axis to point of impact @ 1k yards? Straight lines would be a large presumption I think.. Add a scenario that the groups dispersion is mostly vertical with a little cant counter to Coriolis effect or barrel twist, could this be opposing forces that down range cause your straight line to change?

Ray

 

[BoydAllen]

Perhaps we are looking at the wrong thing. I have been told that long range bag guns can exhibit positive compensation, and that this phenomenon is distance specific. I have corresponded and spoken with a fellow who has done a lot of testing in this area. If a rifle is set up so that its positive compensation is best for 1,000 yards, that factor will play into its grouping at that distance by reducing the vertical that would have been present due to shot to shot variations in velocity, but since compensation is specific to distance, his rifle might not perform as well at a different distance. This would have noting to do with bullets going to sleep.

 

[Joe Salt]

Boyd if I'm reading this correct, positive compensation! This past year I was driving my self nuts trying to figure out why I was having my first shot low. The only thing I changed was I put a sand bag under my forearm to raise my hand so it was in line with the trigger. That cost me some three inch groups at our club and a two and a half at the Nationals. I got rid of the bag when I got back to our club, rapped my thumb back up around the tang and the problem went away. I myself can't shoot like most close range guys do.

Joe Salt