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Different way of calculating a group size

This is a discussion on Different way of calculating a group size within the Accuracy forums, part of the M14 M1A Forum category; Originally Posted by JayKosta ------------------ I understand that to mean that YOU can shoot 2 inch groups with good ammo, but the 'group size' with ...


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Old April 9th, 2017, 05:16 PM   #31
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Originally Posted by JayKosta View Post
------------------
I understand that to mean that YOU can shoot 2 inch groups with good ammo, but the 'group size' with your hand loads was larger.

I think it's important for us to have a 'common understanding' of our terminology. It allows us to talk about things so we all have the same understanding of the words and ideas.

Jay Kosta
Endwell NY USA
Yeah, that's my take on it. Sorry to any that felt I was not being clear. I honestly think I have a QC issue with my hand loads. With factory ammo including XM80 ball and Federal GMM I have only very rare flyers, but I believe my hand loads have slightly better accuracy potential.

Regards,
Badger

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Old April 9th, 2017, 05:30 PM   #32
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Originally Posted by JayKosta View Post
--------------
Hello Rick,

Yes 'mean radius' is a good way to 'characterize' a shot group.

But the term 'group size' shouldn't include analyzing the distribution of the shots in the group - it's just the measured size of the group. I think the statistics about analyzing the group are very useful, but they don't change the group size.

If someone claims to be able to shoot x moa groups, then I expect ALL the shots to hit within an x moa circle (ES).

About 'called flyers' - yes they can be excluded from the group IF you do so BEFORE spotting the hit. E.g. you know you pulled the shot, or there was an obvious mechanical problem involving the shot.
If a shot lands outside of the area you want and you thought it was a 'good shot', then it's probably just one of the expected statistical 'outliers' that make ES size approx 3X 'mean radius' size.

Jay Kosta
Endwell NY USA
Hello Jay, Both Extreme Spread and Mean Radius are methods to characterize a group with a single number. There are always compromises when one attempts to boil a number of observations down to one number. If you feel that Extreme Spread is best for your purposes, by all means use it. However, both methods are totally legitimate to characterize a group. The military uses both in small arms accuracy specifications. One of the problems with using the Extreme Spread method is that it is reliant on the tails of the distribution curve which is problematic. Any value which relies on tails of the curve is generally imprecise and unrepeatable. Values which are derived from the center of the distribution curve are much more precise and repeatable. Rick

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Old April 10th, 2017, 08:58 AM   #33
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Originally Posted by rickgman View Post
Do not forget Sight Picture which is the third main principle of marksmanship. If the sights are aligned but not pointed at precisely the right spot, things are only half done.
Sight picture is a fundamental. Correct sight picture helps the Rifleman achieve proper Sight Alignment. They are interconnected, but not the same.

Sight Alignment

Trigger Control

=

Hit stuff.

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Old April 10th, 2017, 10:05 AM   #34
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Sight picture is a fundamental. Correct sight picture helps the Rifleman achieve proper Sight Alignment. They are interconnected, but not the same.
Well, not really. See what the NRA has to say:

Part 1: Sight Alignment
Intro: The eye is lined up with the top of the front sight, and the location of the rear sight is adjusted (this means moving the gun, and perhaps the head), until an imaginary line between the eye and the front sight passes through the rear sight at the proper spot.

With open sights, having a square rear notch and a Patridge front blade, such as are found on most pistols, the properly aligned front sight should be centered in the rear sight notch, side to side. The top of the blade should appear even with a line extending across the top of the rear sight notch.

When the rear sight eyepiece is an aperture, proper alignment will put the center of the top of the front sight in the center of the rear aperture. Finally, when the front and rear sights are apertures, the eye looks at the front aperture centered in the rear.

Once the sights are aligned, we find a sight picture. To do this, imagine extending the line that defines sight alignment until it touches the target at the desired point of aim. If movement is necessary, move the gun, the shooter and the aligned sights as a unit.

When aiming, your eye should always be focused on the front sight. This is true for two reasons: First, your eye can only focus on one element of a sight picture at a time. The rear sight is too close to the eye to see clearly. If you focus on the target, you will not be able to see the front sight clearly. Second, when you focus on the front sight, you’ll find it much easier to maintain correctly aligned sights through the entire process of firing the shot.

Part II: Sight Picture
Intro: The first priority when choosing the sight picture is to select one that you can see. Generally, four sight pictures are described as useful under a variety of circumstances. They are: “Center of Mass,” “Six o’Clock,” “Line of White” and “Frame.” Each depends on adjustability of the sights to match the circumstances.

Center of Mass (point of aim, point of impact) is simple. Sights are adjusted so the bullet strikes at the point of aim. The aligned sights are placed in the middle of the aiming area and the trigger is pulled.

The Six o’Clock hold is another time-tested technique. The gun is zeroed so that when the aligned sights are brought up even with the bottom of the aiming area, the bullet will strike the center of the aiming area. Target shooters whose guns are fitted with post or Patridge front sights most often use this technique.

Line of White aiming area is halfway between the bottom of the bullseye and the bottom of the target in an area with no reference point. Using a line of white hold puts the aiming area in a blank area of the target where the shooter can concentrate on sight alignment and not be distracted by the bullseye.

A Frame hold is used when the target’s center of mass or the target is obscured or indistinct. It, too, is a target shooter’s technique. A frame hold requires that the shooter center his front sight on the target backer, and frame, completely blotting out the bullseye. As variations, a shooter may center his front sight side-to-side and line up the top of the front sight with the top of the frame, or put the top of the front sight on the top of the berm below the target frame.

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Old April 10th, 2017, 10:33 AM   #35
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It's Monday morning and stuff like this makes my head hurt...

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Old April 10th, 2017, 02:24 PM   #36
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Yeah, me too Ted, but I like to see guys thinking outside of the box. That's how new things come about and new creations are invented.

As postulated, they are not fliers if you called the shot, and you knew you didn't send it where you wanted.

I spend a lot of time on the range. More time than at home actually, and I can tell you something else to watch for when trying to determine your actual group size, as relates to ammo.

Watch your ejection pattern. If all your loads are the same, the brass will be in a neat little pile, ideally sitting at 2:00 from your position. Try to get some help and catalogue each round fired, and where that particular brass landed, as relates to where the round impacted the target. The best way I've found is the Bullseye Target Manager system with it's camera and Wi-Fi link to my laptop. Saves a lot of gas going back and forth at 1000yds.....but knowing where each round is going....priceless.

I think you will be surprised, and find that your so called fliers on the target, that weren't called shots being pulled off by you, will correlate exactly with the empty brass that landed behind you at 4:00, or ahead at 1:00.

The gas system is a closed system. Varying amounts of gas and pressure, from varied ammo make things react differently and affect point of impact.

YMMV, that's just what I've seen.......and a sweet tip for anyone using the Bullseye system, take bug spray and spray on your target, especially if it's white. The system has a rough time distinguishing flies from bullet holes......and I shoot in a cow pasture, so there are many flies.

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Old April 10th, 2017, 03:34 PM   #37
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It would be nice to have a way to measure group size, besides measuring distance between "widest" shots, something that considers width and height of the shots in the group, too.

added: I agree with ripsaw that "calling the shot" is vital to performance and improvement in shooting competition. But it's a tough sell to proclaim that you called that wide shot that spoiled the group and that it doesm't really count in the calculation. For braggin' rights, your great group should be free of errant shots that were called honestly. Shoot another group without excuses.

Inconsistent ammo might send your brass all over the range, but I wouldn't consider that brass dispersion would be a bonafide reason to exclude that shot from the group.
My purpose in shooting groups from the bench is to bring together at one time all the elements needed to produce a great group: bench technique, vision, refined ammo, well built rifle, trigger control, follow through, etc.


Last edited by shooter86314; April 10th, 2017 at 11:58 PM.
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Old April 11th, 2017, 08:32 AM   #38
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Quote:
Originally Posted by rickgman View Post
Well, not really. See what the NRA has to say:

Part 1: Sight Alignment
Intro: The eye is lined up with the top of the front sight, and the location of the rear sight is adjusted (this means moving the gun, and perhaps the head), until an imaginary line between the eye and the front sight passes through the rear sight at the proper spot.

With open sights, having a square rear notch and a Patridge front blade, such as are found on most pistols, the properly aligned front sight should be centered in the rear sight notch, side to side. The top of the blade should appear even with a line extending across the top of the rear sight notch.

When the rear sight eyepiece is an aperture, proper alignment will put the center of the top of the front sight in the center of the rear aperture. Finally, when the front and rear sights are apertures, the eye looks at the front aperture centered in the rear.

Once the sights are aligned, we find a sight picture. To do this, imagine extending the line that defines sight alignment until it touches the target at the desired point of aim. If movement is necessary, move the gun, the shooter and the aligned sights as a unit.

When aiming, your eye should always be focused on the front sight. This is true for two reasons: First, your eye can only focus on one element of a sight picture at a time. The rear sight is too close to the eye to see clearly. If you focus on the target, you will not be able to see the front sight clearly. Second, when you focus on the front sight, you’ll find it much easier to maintain correctly aligned sights through the entire process of firing the shot.

Part II: Sight Picture
Intro: The first priority when choosing the sight picture is to select one that you can see. Generally, four sight pictures are described as useful under a variety of circumstances. They are: “Center of Mass,” “Six o’Clock,” “Line of White” and “Frame.” Each depends on adjustability of the sights to match the circumstances.

Center of Mass (point of aim, point of impact) is simple. Sights are adjusted so the bullet strikes at the point of aim. The aligned sights are placed in the middle of the aiming area and the trigger is pulled.

The Six o’Clock hold is another time-tested technique. The gun is zeroed so that when the aligned sights are brought up even with the bottom of the aiming area, the bullet will strike the center of the aiming area. Target shooters whose guns are fitted with post or Patridge front sights most often use this technique.

Line of White aiming area is halfway between the bottom of the bullseye and the bottom of the target in an area with no reference point. Using a line of white hold puts the aiming area in a blank area of the target where the shooter can concentrate on sight alignment and not be distracted by the bullseye.

A Frame hold is used when the target’s center of mass or the target is obscured or indistinct. It, too, is a target shooter’s technique. A frame hold requires that the shooter center his front sight on the target backer, and frame, completely blotting out the bullseye. As variations, a shooter may center his front sight side-to-side and line up the top of the front sight with the top of the frame, or put the top of the front sight on the top of the berm below the target frame.
You cut and pasted a wall of text to basically say the same thing I just said. Sight alignment and sight picture are not the same thing.

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Old April 11th, 2017, 08:34 AM   #39
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I just use a tape measure. It's pretty brainless and hard to make a mistake...

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Old April 11th, 2017, 10:20 AM   #40
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Sling up, get in prone and make your shots. Shooting from a rest/bags to see what your ammo is capable of only shows what it will do from a rest/bags. Adjusting your sights from a rest/bags only is going to be good for that position. Your rifle will not shoot the same under tension period. Sight your rifle and test your ammo from prone with your rifle under sling tension. Execute proper technique while conducting your course of fire, that will show your ultimate accuracy potential... a sub moa gun and perfect match ammo isn't going to do it. Everything else is academic and meant for pen and paper not holes in paper. If you can't put your bullets through one .30 cal hole at 25 meters (that's actually slightly more than 1 moa) with a super 1 moa rifle your not a one moa shooter, plain and simple. That's a pretty amazing thing if you can do that, I know I haven't done it. Calculus doesn't make you a better marksman and neither does a better gun.

Just saying not picking on anyone

Badger
Please oh please post your red coat target from Saturday am and the one from Saturday pm. The one piece of advise I will give ( everything else posted here is strictly my opinion and is worth to anyone but me and my dog) do not chase your shots, keep the same point of aim. Your groups matter not how your sights are adjusted. Have a great time and show us what you got

Here's mine from my first Appleseed years ago.

Still no mean feat of accuracy but a good improvement over a day
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Last edited by XXIV Corps; April 11th, 2017 at 05:37 PM. Reason: ROE 11, Inappropriate Language, we want this community to be family friendly for all generations.
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Old April 11th, 2017, 10:32 AM   #41
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I have one of these...

https://jet.com/product/detail/23d13...a:2&code=PLA15

Its gives me a quick mesurment that is close enough for me.

Casey

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Old April 11th, 2017, 11:12 AM   #42
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Gentlemen,

I think we've gotten a bit off target. Badger simply explained a method he likes for quantifying group size. It's basically the "Mean Radius" method and is totally legitimate. The US military often uses the Mean Radius Method in accuracy specifications. He wasn't asking about how to shoot accurately - he was just discussing quantification of accuracy. I know many folks don't care to quantify accuracy or use other methods of quantification. That's a matter of personal choice. However, I am often reminded of the following quotation "If you can't express it in numbers....it's an opinion, not a fact!"

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Old April 11th, 2017, 05:03 PM   #43
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Originally Posted by xXRiflemanXx View Post

Badger
Please oh please post your red coat target from Saturday am and the one from Saturday pm. The one piece of advise I will give ( everything else posted here is strictly my opinion and is worth to anyone but me and my dog) do not chase your shots, keep the same point of aim. Your groups matter not how your sights are adjusted. Have a great time and show us what you got

Here's mine from my first Appleseed years ago.

Still no mean feat of accuracy but a good improvement over a day
Again thanks for your good wishes. I'll do that with my targets. I have been practicing on the various 25m scaled 100, 200, 300, 400 m AQT targets. 10/22 is zeroed on a 1" square at 25m. I'm going to wait till the shoot and get some coaching on adjusting the sling properly (using 1" 1907 sling).

The one thing that I think may give me some trouble is my beer gut. I've practiced various shooting positions and there is some pressure on my diaphragm when breathing in sitting and prone. It's manageable but not comfortable. We'll see what happens in 10 days.

Regards,
Badger


Last edited by XXIV Corps; April 11th, 2017 at 05:41 PM.
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Old April 11th, 2017, 05:07 PM   #44
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Originally Posted by Earthquake View Post
I have one of these...

https://jet.com/product/detail/23d13...a:2&code=PLA15

Its gives me a quick mesurment that is close enough for me.

Casey
That is a damn good idea. I am an engineer and I have all sorts of drafting templates even though I've long ago moved on to AutoCAD. I never thought of using those as quick group size gauge. I also have a large circle template that goes from 2" to 4" in 1/4" increments.

Regards,
Badger

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Old April 11th, 2017, 05:10 PM   #45
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I just use a tape measure. It's pretty brainless and hard to make a mistake...
I'm an engineer. It's impossible for me to do it that simple. Must analyze MORE...

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