So What's a GROUP Anyway?


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ChickenHawk
April 13, 2006, 02:27 PM
Just curious about the general sentiment so I can get my bragging rights stated correctly. :)

Example:
If I put 9 holes within 3/4 inch but the 10th is a flyer 4 inches high from the group, what is my official group size, 3/4" or 4" ???

Typical scenario, and my wife will never cut me any slack! :rolleyes:

Cheers,
ChickenHawk

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Bad Words
April 13, 2006, 02:33 PM
I'd call that 10 shots, with 9 in a 3/4" group. If you're going to just go with all or nothing though, I'd call that a 4" group.

WayneConrad
April 13, 2006, 03:16 PM
Old statistician's trick: Call any data points you don't like "outliers" and ignore them so that you get the result you like.

There's a neat trick in the ABC's of reloading. Tape two targets, one on top of the other, exactly aligned, to the target frame. Shoot your group. Go home. Next time you go shooting, do the same, using the same back target, but a new front target. Shoot your group. Repeat this for several sessions.

Now on the back target is the true grouping of your rifle. What appeared as fliers on the front targets are often revealed as just part of the rifle's true grouping.

I've got a target on the wall I'm very proud of. It's an outstanding group. But I got it by shooting group after group in session after session until I got a good one. The group is not representative of what me or my rifle can usually do. It's about a third the size of my rifle's actual normal group measured over many sessions. It is a statistical outlier. It still looks good on the wall, though.

ColoradoKid
April 13, 2006, 03:19 PM
The idiot gunwritwers and testers in the "gunrag media" have been running their tests, showing pictures of the groups, where they disregard a "flyer" and call a smaller group without said "flyer". The justification for this might be that we don't live in a perfect world and "flyers" are part of this imperfect world. Look, nine out of ten in a 3" group and one 1/2" or 1" out, to me is no big deal. Chances are if a shooter is well trained and "tuned up", he will shoot this type of group all day long. Many times, he will shoot more groups in the 3" range and not have a "flyer" to deal with. Shooting is a science and not an art form...!!!

pax
April 13, 2006, 03:38 PM
Gunrag writer here.

The flyer counts: the described group size is 4" and your wife is right.

Unless you can repeat the 3/4" performance with however-many shots you've determined in advance to shoot, then 3/4" is not representative of what you & your firearm can do.

pax

Coronach
April 13, 2006, 03:44 PM
There are rules to determine if outlying points of data should be discounted or not, in the realm of statistics. In the realm of gunwriting or braggin', it is a little more flexible. ;)

Usually if I know I screwed up, before I see the paper, I'll discount the hit from the group. As in, I felt myself jerk and I sent a flyer, that one does nto count for the group. Why? Because it is not an accurate representation of how the gun/ammo combo performs. It is still a valid commentary on how well I performed, of course. The flip side to this is that if I think I shot them all pretty well and I have a flyer or two, I don't eliminate them, because I cannot readily attribute them to human error.

I'm also not 'keeping score' in any real sense. In a real competition (or, worse, in a real shooting) flyers count. ;)

Mike

akodo
April 13, 2006, 04:05 PM
as said, for competion, every shot out of the gun needs to be calculated into a group.

For determining a gun's accuracy, flyers can be taken into account. However, you have to truely be dealing with flyers. A flyer is a shot where you KNOW something went wrong, and can announce that fact before retreiving your target, and probably should be able to tell where on the paper the flyer will appear (went high and left because hot brass from the next lane went down my plumber's crack)

as said, the MOA accuracy of a gun is the size of groups it can produce 9 times out of 10. Just like a stopped clock is right two times a day, just random chance a gun will group shots closer together than the true accuracy of the gun on occasion. This does not work in the reverse, however, outside factors such as a change in breeze, barrel heating, shooter fatigue, etc can cause 'quasi-flyers' - shots that are a little off not due to the gun but due to the shooter.

I think the best method of determining how good of groups you or your gun can shoot is a trimmed mean. Shoot X shots 10 times, drop the best target and the worst target. measure the remaining 8 and average them.

ChickenHawk
April 13, 2006, 04:23 PM
Ah but for the days in college when we could drop our worst exam grade from our average.

I guess I knew from the outset that flyer must count. :o

Like Coronach, I don't have to see it to know that one went high (or whatever); you KNOW when you make that bad shot.

BTW, I haven't got a single long gun. I'm all handguns. Don't try to talk me out of that. I have a disability and holding a long gun isn't too easy for me.

I really love the idea of re-using a "back" target. In reality I don't know if I can keep a target that long, though! I tend to use those targets which have a large bulls-eye in the center and 4 smaller ones around. I warm up at 15 yards on the center target, then get serious on the smaller outer bulls-eyes. Those are the ones I count. After that I'll shoot the center some more. I usually end up with a fist-sized center completely blown out. Then I get a fresh target and do it all again.

My best target ever was shot as described above but has ONE crummy hole a few inches above-right of the center bulls-eye. Darn it! I could have cried.

My wife will give me one in the ribs when she reads this thread.

Great replies, thanks!
ChickenHawk

M2 Carbine
April 13, 2006, 08:03 PM
When just shooting for recreation, if I know I blew a shot, I'll call the group the size of the 9 shots but if I thought all 10 shots were good then I have to include the flier.

For instance, the last couple weeks checking out what the Kel Tec PLR-16 pistol will do. I knew I blew that shot before I looked.:(
So, I say the gun shot a 1 1/2 inch group this time.

http://img.photobucket.com/albums/v135/Bell406_206B/PLR95ydsPMCmatch3226.jpg

ChickenHawk
April 13, 2006, 09:02 PM
I like the way you think M2!! See, that's the answer I was looking for ;)

Unfortunately, my wife will not notice YOUR post! :rolleyes: But I know she'll read me all of the others.

Regards,
ChickenHawk

Standing Wolf
April 13, 2006, 09:09 PM
Unless you can repeat the 3/4" performance with however-many shots you've determined in advance to shoot, then 3/4" is not representative of what you & your firearm can do.

Unless, of course, the firearm's manufacturer is a big advertiser in your gun magazine, in which case, discard the flyer and praise the pistol to the skies.

pax
April 13, 2006, 09:15 PM
Standing Wolf,

As a writer, I never have done that, and I do not appreciate your sarcastic insinuation that I might.

pax

redneck2
April 13, 2006, 09:23 PM
As a writer, I never have done that, and I do not appreciate your sarcastic insinuation that I might.
He never said that you would. As Will Shakespear said "methinks ye doth protest too much"

While groups are great, IMO a 3 shot is probably the most important. It gives a true indication on the quality of performance of the firearm. Actually, one shot is all that really matters if you're a hunter, but it totally disounts human error.

pax
April 13, 2006, 09:54 PM
redneck ~

He quoted my post -- a post in which I clearly identified myself as a "gun rag writer." And he used second-person sentence construction ("your").

As far as I can tell, that was a personal insult/attack -- the sort of thing which isn't allowed on THR per forum rules. And so I'm waiting for my apology.

Btw, re the number of shots in a group, I've always thought 5 was a pretty good measure. Three can give you flukey results.

pax

Standing Wolf
April 13, 2006, 11:48 PM
Standing Wolf,
As a writer, I never have done that, and I do not appreciate your sarcastic insinuation that I might.
pax

Hello, pax!

Sorry if that seemed personal. 'Twasn't so intended. Please do accept my apologies for the confusion.

I meant to take a cheap shot at gun magazine writers in general, who can always find at least five good things to say about an advertiser's gun, no matter how patently obviously inadequate the firearm might be.

I still buy and skim a few gun magazines, but must confess I pay closer attention to the advertisements than the purported "content," the lion's share of which consists of rewritten press releases. I'd be hard-pressed to tell you which is more poorly written: the original press releases or the so-called "articles." The two notable exceptions are reloading and gunsmithing articles, many of which are based on actual research and/or experience, and a few of which are written in ordinary, intelligible English. Sheriff Jim Wilson of Shooting Times occasionally writes a worthy historical column, but his "product reviews" are like the rest: sorely lacking in intestinal fortitude.

I am, indeed, a snide, sarcastic individual, but honestly can't recall an instance of sniping at fellow High Roaders.

pax
April 13, 2006, 11:50 PM
Thanks, Wolf -- I was pretty sure that was the way you meant it, but it sure sounded personal.

:)

pax

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