the wind can't

[bruce moulds]

be my friend if it doesn't blow.
bruce moulds.

[AlanF]

Yes Bruce. We share that aspect with sailing. In the Americas Cup, they postpone competition if the wind doesn't get up. Do you think we should do something similar at Queens?

[RDavies]

Ooops, so my philosophy is wrong?????

The wind is my friend when it blows all wierd, when someone else is shooting, then gives me the nice calm eye of the cyclone.

[Paul Janzso]

OK Rod , I have seen you wish that on competitors at the Canberra Queens, how do you do it?

Paul

[bully_eye]

I was shooting out at SSAA Silverdale recently and was chatting to a VERY accomplished benchrest shooter. He gave me an excuse I've never heard before but have since added to my book. He said that it was useless shooting for group because there was NO WIND. To qualify his statement it's just one of the local conditions where zero wind equals shots out of the group due to elevation but I honestly thought I had heard all the excuses.

[williada]

Bully-eye,The benchrest shooter’s observation is not as dumb as it sounds. Zero winds can create variable air densities which will open the group and are very hard to tune for and not worth chasing in terms of tune unless this is a dominant condition where you shoot.

If there is denser vegetation on the edges of the range, thermals develop because the centre of the range is relatively hotter and draws in the cooler air from the edges which then rises and rotates

Importantly, low pressure rising air spirals inward in a clockwise direction in the southern hemisphere but high pressure sinking air spirals anti-clockwise and outward. The projectile impact mirrors the atmospheric activity. Reflect on those left right groups, clusters and flyers.

What complicates picking the bullet impact, is that more than one thermal can be operating on the range at one time as mini thermals; and in the case of a mini thermal you may be shooting on the left or right of its centre and so your bullet impact can be completely different from those shooters squadded to the left or right of you. Other complicating factors are the thermal half develops or cold air overwhelms the rising air and bullet displacement actually appears to reverse go wide and low. This can be very tricky in the morning.

The range terrain also influences the behavior of the thermal. Vegetation may be higher on one side producing more moisture and more variability. The slope of the range, mound height and gullies may retain denser air but they also block thermals moving back and forth along the range. Ever had those great shoots at one distance, but to fall in a heap at the next?

Air variables, in zero winds, also defract the light causing mirage density to change and aim-point errors. It also leads to overestimating and underestimating the mirage and corresponding windage. Have you heard shooters say, “It was stronger from the left than the right when the mirage ran or when it boiled I went high or then low when it ran.” Or other shoots say, “I never touched the sight.” So one can see, that the thermal effect on bullet deflection can have something adding or countering it. Its easy to get lost altering on your shots rather than hunting and pecking the conditions or shooting in a window of conditions.

The scores of other shooters tell you that something is at work. Look to where the best scores are coming from and I’ll bet the terrain and the vegetation are the major influence in zero winds. So where would you like to be squadded? Me, in the centre, or on the edge with the lowest vegetation with a tendency to keep a low group.

Shooting on cold days without thermals and good sighting in zero winds is easy.

I prefer to shoot when its windy, but that’s another yarn.
David

[bully_eye]

Thanks for that. I certainly wasn't doubting what this shooter was saying- I regularly see world championship level benchrest shooters out there- and I've experienced those strange flyers he was talking about. I just thought I'd heard or used most of the excuses and no wind was just a new one to add to my list.

Thanks again,
Michael