SHOOTER ABILITY AND CONDITIONS

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joeb33050 posted this 17 October 2018

 

If not for some error, such as wind or barrel harmonicas or shooter error or case weight variation, all the bullets would go through the same hole. The sum of all the errors, assuming a NORMAL distribution of shot location, is the standard deviation. I model group size by entering imaginary average group size and standard deviation.

 

In analyzing the ratio: largest group / smallest group, I found that my center fire records for five, 5-shot groups averaged 1.979, close to the expected 1.91; and assumed that this was a fluke-my records being so close to the expected.

 

Then Larry Landercasper posted his records, averaging 1.980 vs. expected 1.91.

 

Our records, Larry’s and mine, are with one shooter, in a tunnel. My range has close dirt hills each side, and virtually no wind.

 

The NRA, CBA and IBS records are substantially larger than expected, have wind, and many shooters..

 

I suggest that the difference is due to wind, (conditions), and number of shooters. Then conditions and shooter ability have a large effect on group size;  maybe larger than we supposed..

 

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RicinYakima posted this 17 October 2018

Then conditions and shooter ability have a large effect on group size;  maybe larger than we supposed..

I believe you are correct in that suggestion.

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onondaga posted this 17 October 2018

Joe, I don't believe you are correct about 1.91" as an assumption for group size. Consider that you can be just a mediocre shot with mutilated chamber rifles from brutal gunsmithing and changing barrels and modifying reloading dies. You leave out those variables selectively to get people to agree with you. That doesn't work for me. Your premise is very flawed and lacking factual factors about yourself and your rifles. You look for arguments then complain to the management when you get them.You really pick on Savage rifles too. They shoot fine if you just leave them alone instead of what you do to them. The ideal cast bullet fit is not a hidden secret, and is still what makes them shoot well in plain Jane factory rifles with standard chambers and bores. You disagreeing with that is what causes 1.91" groups.

Gary.

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joeb33050 posted this 17 October 2018

Joe, I don't believe you are correct about 1.91" as an assumption for group size. Consider that you can be just a mediocre shot with mutilated chamber rifles from brutal gunsmithing and changing barrels and modifying reloading dies. You leave out those variables selectively to get people to agree with you. That doesn't work for me. Your premise is very flawed and lacking factual factors about yourself and your rifles. You look for arguments then complain to the management when you get them.You really pick on Savage rifles too. They shoot fine if you just leave them alone instead of what you do to them. The ideal cast bullet fit is not a hidden secret, and is still what makes them shoot well in plain Jane factory rifles with standard chambers and bores. You disagreeing with that is what causes 1.91" groups.

Gary.

 

Well, Gary, you've not understood what I've written. There's no assumption of 1.91" group size. 1,91 is the EXPECTED RATIO of largest / smallest group sizes in sets of five, 5-shot groups. 

You don't understand it, your comments are thus nonsense, and you've embarrassed yourself once again. Perhaps your bore is TOO shiny.

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onondaga posted this 17 October 2018

It is great you have a sense of humor, nonsense is always debatable.

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Ross Smith posted this 18 October 2018

Well Joe you lost me too. Just what is 1.91?   Inches? And is the 1.91 the difference between largest and smallest group?

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RicinYakima posted this 18 October 2018

I am fairly sure that Joe is saying: "If the smallest group I shoot is 1.00" the largest group would be 1.91"."  And that is for lots of five shot five-shot groups.

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GP Idaho posted this 18 October 2018

I agree Ric. What I took from Joe's math is that if you used the exact same load repeatedly that do to standard deviation your worst group would be nearly twice as large as your best. correct me Joe if I'm not getting the gist of it. Gp

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joeb33050 posted this 18 October 2018

Shooters frequently reach conclusions based of very small samples-the "Wallet" group. Many years ago John A. and I were attempting to convince others of the need for more data. I went to stats and concocted an example: ON AVERAGE, if you shoot five 5-shot groups, the largest group will be 1.91 times the size of the smallest group. And, the 1 group shooter doesn't know which of the 5 or 10 or 4 groups his is. 

Later I solved for 2 to 10 shots per group, and 2 through 10 groups.

Analyzing data, I found this ratio, largest / smallest, to be very valuable.

And, accidently, found the N RA lying to us.

Is that clear? (I used to tell the kids in class that if they didn't understand, it was MY fault. Obviously I haven't been clear.)

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Ken Campbell Iowa posted this 18 October 2018

... i just realized that between joeb and you-tube, i wasted 5 years of no-sleep at advanced high school .... i coulda got in more coyote hunting !! ....

.... oh well, next time around !! ....

ken

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rmrix posted this 18 October 2018

Having been for many decades a competitive cast bullet shooter, I have looked with interest at the many ways the hunt for accuracy is evaluated. Statistics are cited with hard rules and minimum shots (data points) and comments about others test based on claims of invalid data.

 

It is baffling the various correct way to this as reported far and wide.

I have never taken statistics. Likely many of the people I compete with have little understanding of it either. IMO through conversations, most likely even the most successful competitors rely on "best impression" to guide us.

 

With the title of this thread in mind; Shooter Ability and Conditions ....

One thing is certain for a rifleman to be in the winner circle.  As the ranges to the target increase, the need for accuracy lessens, and basic rifleman skills and condition reading skills take over.   In other words, the advantage a 0.5 MOA rifle has over a 2.0 MOA rifle evaporates in real life conditions shooting cast bullets from 300 yards to 1000 yards. BTW- I'm very sure I never competed against anyone with an honest 1 MOA rifle. I hear about them ALL the time on the internet. Funny, few to no one ever has one at the match.

 

I am still interested in finding a "better way" so I am reading and looking to learn.

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Ross Smith posted this 18 October 2018

Joe: Thanks, that explanation helped. 2 will be easier to remember though. I'm seeing this "situation" with the Ardito rifle I bought. Lot's of learning involved.

rmrix: I'm learning about the moa rifle now. My view is that you might be able to buy a .5moa rifle, but that doesn't mean you are going to shoot .5moa. But gettin there is fun!

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