OzFclass

Hi All
The 3 targets below where shot at 500m, I also chronygraphed the results, which set of results go with which target ??
North Sydney members please don't answer
Chrony results:
A ES 9.3 and SD 3.2
B ES 20.6 and SD 6.4
C ES 32.6 and SD 8.2

Matt P

My guess is
A. Tgt 2.
B. Tgt 3.
C. Tgt 1. (The top one)

How many guesses do we get..

Wild guess with only one dimension of information.

Wind speed and windage correction by hold or winding would add a further dimension to the equation!

I really don't see how anyone could accurately determine an answer other than the highest ES-SD figures goes with the tallest group with what you have provided.

What's the gag?

No correction, L-R less than 3 MPH.

Matt,

I'm guessing you were using a SAUM and Berger 180s at about 2950. If you weren't then the following calculations may be slightly different.

The worst ES you had was 32 fps. At 500m this on its own will cause 43mm vertical. BUT, the best vertical of your 3 groups (the middle one) was very close to the height of the X ring, which is 72mm!

Conclusion 1 : Any of those velocity figures could go with any of the groups.
Conclusion 2 : There are clearly other things going on (than velocity variation) which are causing some vertical.

So my guess is that the middle group had the worst velocity variation (unless this is a very cunning reverse psychology trap ).

Alan

Ok, it was with a 6BRAI, using 108's @2950.
Target 1 had the ES of 9.64 and SD of 3.2
Target 2 had an ES of 20.6 and SD of 6.4
Target 2 had an ES of 32.6 and SD 8.2
It shows that numbers aren't everything especially back to 5-600, now the first load may be able to tuned with some seating depth adjustment.
Maybe weighing primers might help
Matt P

And, I was going to say that the first stage was target C
The second stage was target A and the final stage was target B.

This is based purely on an in-depth analysis of what I would expect from the grouping.

ShaneG wrote:Wild guess with only one dimension of information.

Wind speed and windage correction by hold or winding would add a further dimension to the equation!

Target 1 shows a lot of vertical, I've never seen that kind of spread due to wind.
Matt P

None out of three. Bugger.

Where's the like button! What was the sighting conditions ? Because that's the only thing could explain it! Other than that

Been thinking which is a bit hard for me lol! Some wicked barrel whip going on maybe?

plumbs7 wrote:Where's the like button! What was the sighting conditions ? Because that's the only thing could explain it! Other than that

Been thinking which is a bit hard for me lol! Some wicked barrel whip going on maybe?

It makes sense since it was only shot at 500M. If the node is fairly wide and the load is smack bang in the middle of the node, then at short ranges (500M), you can still get decent accuracy. When he changed loads and the ES/SD improved, it was likely going out of the node, either over or under it. Short range BR shooters (out to 200-300yds) dont weigh charges, cases, primers, bullets, or batch by seating tension, bearing surface etc etc because ES/SD doesn't matter much at short range (within reason) as long as the load is in tune.

Now lets see how the load with the big ES/SD goes at 900-1000yds.

Are the velocities your getting from an ET? Is this accurate enough to give reliable measurements?

From what I've seen FO calibers pushing the high BC bullets at high velocity hold accuracy out to 800ish yds even with often poor ES.

I went back and looked at the groups again and it hit me what the issue is. Everyone has been overlooking the most poignant question.

RDavies wrote:I went back and looked at the groups again and it hit me what the issue is. Everyone has been overlooking the most poignant question.

What , what ? I can't watch karate kid now!