Scientific explanation please

[Abboshi]

This is my first post.

My friend was long range shooting with his 556 and saw his bullets spiral at the end of flight.
Distance was 1 kilometer, Lithuanian 62 gr. Tracer Ammo . (1/9 twist 20” barrel) .

I would appreciate it if someone would explain the reason behind this.

Video

 

[_Windrider_]

Because at that range the bullet is unstable and is tumbling. 1000 meters is a long ways away for the mighty 556, especially for a tracer

 

[Rocketmandb]

Is that a Mil or MOA spiral?

 

[mark5pt56]

Think I saw some spin drift!---yeah, yeah went Ricky rack after hitting--

 

[Nvcnvc]

Because at that range the bullet is unstable and is tumbling. 1000 meters is a long ways away for the mighty 556, especially for a tracer

x2! that is the most likely reason. Can't tell for sure without looking at the bullets to see if they had a deformity that could have caused a bad spin...when bullets transition to the transonic area they experience turbulence that can caused them to tumble...

 

[pmclaine]

It's also 62 gr. tracer ammo.

I wouldn't call it match and would expect as it burns it's load of phosphorous or whatever it starts to get screwy.

 

[cas6969]

I just kept watching it over and over without realizing it, thinking "Damn it's still pretty good, damn consistent!"

I wouldn't be shocked at anything funny a tracer did, it's got a little pitch and yaw rocket stuck in it's ass.
Put one in your ass and try to walk straight!

 

[whatsupdoc]

FIREARMS TUTORIAL

Page contains images and text for pathology education

webpath.med.utah.edu

Bullets do not typically follow a straight line to the target. Rotational forces are in effect that keep the bullet off a straight axis of flight. These rotational effects are diagrammed below:

Yaw refers to the rotation of the nose of the bullet away from the line of flight. Precession refers to rotation of the bullet around the center of mass. Nutation refers to small circular movement at the bullet tip. Yaw and precession decrease as the distance of the bullet from the barrel increases.

 

[Terry Cross]

This is my first post.

My friend was long range shooting with his 556 and saw his bullets spiral at the end of flight.
Distance was 1 kilometer, Lithuanian 62 gr. Tracer Ammo . (1/9 twist 20” barrel) .

I would appreciate it if someone would explain the reason behind this.

Video

You mentioned that this occurs toward the end of the flight path, so I will assume it is not occurring early at closer ranges.

If this is true, my bet would be that those tracer rounds are going trans-sonic before impact. Tracers are notorious for not transitioning cleanly and are squirrelly AF at distance because their cg is changing the entire flight.

At your videoed impact location there could even be some wind compression and crazy updraft swirls going on right at the rock face aggravating the above condition.

or not.....


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