Precision and Accuracy
Oh, I understand it now. Thanks Nimrod
Oh, I understand it now. Thanks Nimrod
For precision and accuracy determinations
Determining Minutes of Angle(M) subtended on target:
M=60[ Tan -1 (group size in inches/range in inches)]
where M= number of minutes of angle subtended or 1 min = 1/60 degrees = 1.047 inches at 100 yards
Minutes of angle subtended by a target group at 100 yds.
M = Target group size (inches)/ 1.047
Determining Standard Deviation (target precision or velocity)
s.d. = square root of sigma(dn)2(squared)/N-1
where s.d. = standard deviation(precision = inches, velocity = feet per second)
dn = vertical distance from reference line in inches(precision) or velocity deviation of individual round from average velocity in feet per second (velocity)
N = number of rounds in group
These are a few formulas I use to determine MOA, velocity, and precision of individual handloads. These take a good bit of human error out of measuring groups with a ruler and/or micrometer. There is a complete chapter dedicated to using these formulas in Precision Handloading by John Withers.
:-D
M=60[ Tan -1 (group size in inches/range in inches)]
where M= number of minutes of angle subtended or 1 min = 1/60 degrees = 1.047 inches at 100 yards
Minutes of angle subtended by a target group at 100 yds.
M = Target group size (inches)/ 1.047
Determining Standard Deviation (target precision or velocity)
s.d. = square root of sigma(dn)2(squared)/N-1
where s.d. = standard deviation(precision = inches, velocity = feet per second)
dn = vertical distance from reference line in inches(precision) or velocity deviation of individual round from average velocity in feet per second (velocity)
N = number of rounds in group
These are a few formulas I use to determine MOA, velocity, and precision of individual handloads. These take a good bit of human error out of measuring groups with a ruler and/or micrometer. There is a complete chapter dedicated to using these formulas in Precision Handloading by John Withers.
:-D1 - 15 of 15 Posts
cool but...
i've got a 2 year college degree, but i think i'll still just use the 'ol dial calipers'. i hate thinkin. :wink:
i've got a 2 year college degree, but i think i'll still just use the 'ol dial calipers'.
i hate thinkin. :wink:HA.... I'm with KYODE I too have a 2year degree but I'll just use the calipers
I'm with KYODE I too have a 2year degree but I'll just use the calipers
You guys stopped too early. I have a four year degree and use a 12" three sided ruler marked in 10s of an inch. You're kidding yourself if you try to measure closer than 1/10".
GB
GB
Alright already, So I don't have a drinking problem - just a hobby problem. Wait , I don't have any hobbies just obsessions!
I can't believe no one caught the "sigma" in those formulas that was not defined. I've used those formulas for ten(10) years and still have to go to the book when I sit down and do my calculations. They actually look harder then they really are.
Graybeard, I sat down last night and put together a .27" group (actually only two shots) using a 7mm bullet. I had three different people measure it and came up w/ three different measurements. I guess my point is the amount of error in measuring holes that close together. Pretty impressive group all the same from a 7-30. (This is where all those formulas came from!)
Kyode - you should know me better than that - I'll post the formulas at Gary's place and see what the guys say!
I can't believe no one caught the "sigma" in those formulas that was not defined. I've used those formulas for ten(10) years and still have to go to the book when I sit down and do my calculations. They actually look harder then they really are.
Graybeard, I sat down last night and put together a .27" group (actually only two shots) using a 7mm bullet. I had three different people measure it and came up w/ three different measurements. I guess my point is the amount of error in measuring holes that close together. Pretty impressive group all the same from a 7-30. (This is where all those formulas came from!)
Kyode - you should know me better than that - I'll post the formulas at Gary's place and see what the guys say!
i agree
to each his own sounds good. if i'm just messin around i'll just measure with a tape rule for a close estimate. but if i get excited and it looks like a new world record (for KYODE) then i pull out the dial calipers, if i remembered to bring em. :lol:
whats a sigma ! :?
to each his own sounds good. if i'm just messin around i'll just measure with a tape rule for a close estimate. but if i get excited and it looks like a new world record (for KYODE) then i pull out the dial calipers, if i remembered to bring em. :lol:
whats a sigma ! :?
Re: i agree
I think that's a S&W handgun isn't it? Or is that a stigma?
GB
KYODE said:whats a sigma ! :?
I think that's a S&W handgun isn't it? Or is that a stigma?
GB
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