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Elliptical Swerve

Broz said:
...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"...

... 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) ...

Jeff
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Mikecr,

Are you trying to say that what Jeff's experiencing is impossible? ^^

Trying to keep up here... :rolleyes:
 
Here is a couple of sentences, from that linked paper, by Bryan Litz.

The bottom line is that epicyclic swerve cannot cause smaller angular groups at longer ranges. ............ The phenomenon of smaller angular groups at longer ranges was not disproven. The only thing I've shown is that if the phenomenon actually happens, epicyclic swerve is not the cause of it
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I am sure some will think this is an uneducated question. But, who says this problem or phenomenon has to be angular?

And also I have never said the groups get smaller in measurement, only smaller in minutes of angle and the same in inches.

Jeff
 
Broz said:
I am sure some will think this is an uneducated question. But, who says this problem or phenomenon has to be angular?

And also I have never said the groups get smaller in measurement, only smaller in minutes of angle and the same in inches.

Jeff
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You said it was angular.
 
Edd said:
You said it was angular.
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I did? where? I take an angular error as increasing in diversion or measurement with distance? I never meant to imply that the groups got larger at 200 or 300 yards but tried to be clear the stayed the same in measured inches.

Jeff
 
Visually trying to predict what would happen. If a bullet is fired into a liquid such as water and the bullet strikes the water with the nose pointed fully forward what path would be invisioned as the bullet traveles through the water? If a bullet is fired into the same liquid with the nose not pointed fully forward but rather with a slight "tilt" what path would be invisioned as the bullet traveles through the water? Are the same path invisioned for both? Is not a bullet cosistently trying to maintain nose forward postion? Would this invisioned path in liquid be somewhat of a back and forth motion? Is not air also considered a fluid?
 
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Much as I enjoy the endless debate over epicyclical and elliptical deviations to bullet flight paths (tongue firmly planted in my cheek) there is the underlying thread of trying to explain observed empirical data i.e. apparent improvement of group moa at range.

My two cents:
MikeCR is probably closer to the factor as our equipment (scopes) have a reduced parallax factor at greater range and optically the longer ranges compress (sort of) the differences of the target and reticle optical planes. Notice how the parallax adjustments from 10 yds to 100 yds are so great but a small turn in the adjustment then corrects for 100 yds to 1000 yds? And atmospherics have a huge effect on accuracy at long range.

I have observed the same decreasing moa accuracy with increasing range but my pony in this race is believing that other factors have diminishing effect on the group size. A very slippery high BC bullet is less affected by the air and therefore HAS a lesser effect on the bullet path due to its interaction with the air. Their much greater weight and higher gyroscopic stability keeps them on path. When a gyroscope starts to wobble (epicyclically that is - LOL) it generally doesn't wander around much on the floor. It just wobbles worse in the same place.

The B70 Mach3 Bomber had wing tips that drooped into the shock wave while at top speed for two reasons:
1) To maintain stable forward flight.
2) To have sufficient control surfaces to move off of stable forward flight.
Something moving Mach3 has a bunch of momentum keeping it on path. It takes a pretty good slap to knock it off that path.


Something like 65,000 psi of 7000 degree Fahrenheit almost-a-plasma burning gasses hammering a not so perfect bullet base exiting a poorly made muzzle comes to mind...


KB
 
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