Highly Visible Trajectory

[pjifl]

Just returned from the NQ Queens in Mackay.

I always take a special very large set of high power binoculars to shoots and they stay alongside the scoreboard.

On Friday afternoon just before the setting sun we could easily watch
projectiles for the entire 900 yards.

Not just the heated wash from bullets which is easy to see.

The sun reflecting from them. The trajectory was high enough to
catch the sun but the background in the eyepiece was a dark mountain and they were just so clear. Clearer than I have ever seen.

Anyway - not only was the basic trajectory very visible but so was the
corkscrew motion. I wish I could have glued myself to it while different
cartridges were fired. You could see that in some the magnitude of the
corkscrew was much larger than others.

There is nothing new here. Moments and Yaw and Gyroscopic Precession are all well known but somehow seeing is REALLY beleiving.

Sometimes this corkscrew is visible on the heat track from a bullet but is very hard to quantify.

In contrast, here one could mentaly quantify the effect by relating to the apparent size of the target rings. The apparent angular diameter of the corkscrew looked about 1/2 to 1 minute across.

One thing of great interest. During one shoot - ie with the same cartridge - sometimes the magnitude of the corkscrew was larger. And the impact was usually an 8 further from the target centre. Again, this is not unexpected.

Whether this was induced by an extra flick from the wind or yaw at launch or even a degraded projectile I dont know. Conditions were not severe but were a bit twitchy.

Peter Smith.

[Simon C]

We get treated to a similar experience at our club this time of the year..but mainly beyond 700m...the sun tends to be lower behind us which allows u to see the shiny base of the bullet and the vortice it creates on its travel. Likewise, there is a dark patch of scrub in the distance behind our backstop that enhances the view. It certainly helps you to 'picture' the trajectory...

[RDavies]

It would be good to check this out in good conditions again. I wonder if flat base bullets/vs boat tail or whether fast twist heavy bullets VS slow twist lighter bullets or whatever would show different corkscrews? I wonder if a realy accurate rifle/load/caliber would show less corkscrew than one which does not group as well?
I think it was while using your big eyes binoculars you made and looking through my scope that I have seen the corkscrew motion. It looked like the bullet was buzzing and vibrating around on its way to the target.
It will be good to compare some realy accurate guns with some which just arent shooting well.