Range Report - 7x300 Weatherby - 5-28-15

Started by gitano, May 28, 2015, 09:34:16 PM

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gitano

And finally, my 'baby'. The rifle that has NEVER let me down. I shoot one bullet from this rifle - the Speer 115-grain HP. It has ALWAYS shot 'like a laser'. The box of ammo I am shooting from is the last of a box loaded in the late '80s. It's AT LEAST 26 years old. Including today, I've shot this rifle twice in the last 25+ years. There's no need. It shoots right where I point it. :D EVERY TIME.

Here's the target at 100 yd.


That's three holes. The first shot from the 'cold' barrel is half a caliber off of point of aim. The other hole is the second and third shots. The MVs are 3462, 3467, 3465, average 3465 and a max spread of FIVE feet per second. :D Oh yeah, the only scope this rifle has ever had on it is a crappy Tasco.

See here http://thehunterslife.com/forums/showthread.php?t=16867 for "the rest of the story".

Paul
Be nicer than necessary.

gitano

#1
Here's my statistical analysis:


Of primary interest to me is the value for the Area of the 95% Confidence Ellipse seen in cell "F16". For this three-shot group, that value is half a square inche. What that values predicts is the area into which I could expect the next 95 out of 100 shots to go at 100 yd.

If you look at cell "B3" you will see the value of "Student's t". That value is based on the sample size. The larger the sample size, the smaller the Student's t value. The Student's t value is a MULTIPLIER of the variance observed in the shot string. Therefore, the greater the number of shots you are using to determine the parameters (average, variance, etc.) the better the estimate of 'reality' you will have. Since the smaller the sample size the less confidence one has that the samples used actually REPRESENT REALITY, you have to broaden the PREDICTED parameter.

Taking "max spread" as an indicator of THE BOUNDARIES AROUND where the "next bullet" is going to hit is "optimistic" at best. Put another way, it's fooling yourself. There are PLENTY of people in the world that want to fool me, I don't need to fool myself. What I want to know is my BEST GUESS at where the 'next' bullet is going to hit based on where the last "X number" of them hit. Max spread is "easy", but it's not "good" for making that prediction/guess.

Paul

PS - If you have MicroSoft Excel and would like a copy of the spreadsheet so you could perform your own calculations, shoot me a PM and I'll email a copy with some instructions to you .

Paul
Be nicer than necessary.

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