Interesting thoughts on 'shooting groups'

[AJMD429]

Found this here - http://www.public.iastate.edu/~jessie/P ... 0loads.htm

Testing loads

When comparing loads we generally use group size as a measure of accuracy. In general group size is very easy and convenient to use as a measure but lacks statistical rigor. As with most things, the most powerful statistical tool is hardly the most convenient so I have attempted to draw a compromise between convenience and a powerful method.

So what is a powerful method? It is a procedure which provides the user with two things: First, a high degree of confidence that the differences between two treatments (e.g., accuracy of two different loads for a target rifle) are indeed real. And second, a high degree of confidence that finding “no statistical difference” means there is truly no difference between the two treatments.

Let’s deal with the first part. If I shot a 10-shot group with an inexpensive .22 ammo like Wolf Match that was 1.25” at 100 yds and another group with Eley Tenex that was 1.125” would you really feel confident that Tenex is more accurate? Maybe. Would you feel confident enough to invest in a case of Tenex? Probably not. You would probably shoot another group or two with each ammo and see if Tenex continued to beat Wolf Match. If you, in fact, did this, then YOU ARE using statistics – not in the formal sense but in the by-the-seat-of-your-pants-sense. Sometimes the seat-of-your-pants is good enough. Sometimes it is not. And wouldn’t it be nice to know just how confident you can truly be before you plunk down the green for a brick or two of the Good Stuff? And if by chance you didn’t find much difference between Wolf Match and Tenex, and so chose Wolf, just how sure would you like to be that you have the right stuff when you lay down to shoot for the money against someone that has all the bells and whistles and knows how to use them?

Well as I mentioned, there are EASY ways and there are BEST ways and there are ways in between. Before describing what I feel is the optimal the compromise, let me address the EASY and BEST ways and illustrate their up sides and down sides. If you want skip through all this boring BS, just find the section that begins with “The 2-Shot Way”

The EASY Way is what most of us do and what you read about on the internet over and over. We shoot groups. Some of us believe in 3-shot groups, some in 5-shot groups. Some hard-core guys like no less than 10-shot groups and a few gun cranks are not happy with less than 20 or 30-shot groups. However it is done, it is easy. All you have to do is measure the longest distance across the bullet holes and you have a number. Do that for each of two or more loads and you are ready to make a decision. That’s the upside – it’s EASY.

The down side is that if you do this again, you might not get the same result. The load that had the slightly better result the first time, might have the worse result the second time. Then what? Do it again? How many times do you have to do it, before you are happy that you know which is best? How do you know if you should even BE happy in the first place? This is one of the two major down sides – No quantitative degree of happiness (more on measuring “happiness” later).

The second downside is that if you shoot a large number of shots, most of them will not go into the calculation of anything. Suppose you shoot 30 shots per group, what does it mean? It might mean that one or two of the shots that actually were part of the largest dimension of the group happened to be aberrant for some reason of which you are blissfully unaware. A bullet could have a void or a primer might be bad or a fluke breeze might have puffed up, or a particular bad moment of mirage might have occurred or any one of dozens of possibilities could have resulted in that one shot that goes just a little wider than all the rest. How do you know it not a fluke totally unrelated to whatever it is that you are testing (e.g, two different powder charges)? The answer is you don’t, you can’t and you can only fool yourself if you think you can always detect such “demonic” events, yet that one bad moment provides the only measure of accuracy for that entire group and all the other shots are effectively wasted. If you could somehow use ALL the shots you would at least dilute the biased caused by this one anomaly and thus get a truer estimate of what is really happening out there.

So how can we use ALL the shots?

...........the rest of the article has graphics so go look at the original -
http://www.public.iastate.edu/~jessie/P ... 0loads.htm

[Blaine]

I believe in The One Shot Group

BANG
Did you hit it?
Yes.
Good Group.

Not a joke at all. Everybody has shooters that might not shoot the smallest groups, but that almost always seems to hit what you're shooting at.

[jdad]

If I shot a 10-shot group with an inexpensive .22 ammo like Wolf Match

I don't consider 0.15 per round inexpensive.....for "match" ammo maybe, but....

[Griff]

Makes my head hurt... The EASY way, and I can go to bed happy!

[Old Savage]

The only real accuracy need I had was hunting. #1 where did the first shot go from a cold fouled barrel? #2 where did the next shot go.

[Old Ironsights]

When shooting groups I prefer battalion level TOT.

If I can't get that, a mortar platoon or nearby Zoomie is a useful alternative.

However, if it's down to just me and a Group, nothing beats properly placed IEDs &/or falling buildings...

[Sixgun]

Makes my head hurt... The EASY way, and I can go to bed happy!

I was just thinking the same thing. If I have to analyze my group shooting like that, I might as well call the plant to see if I can get my old job back..........and that's as much fun as sleeping in a bed with a rattlesnake. Geeze , give me a break.....shootin's supposed to be fun.-----6

[J Miller]

Well, my thought on "shooting groups" is that you need a horizontal spreader on the muzzle of the shotgun.


Joe

[mikld]

I don't compete so I don't want to take the fun outta my shooting with a bunch of statistics or formula. I shoot groups nd normally "test" loads with multiple rounds (not cartridges, but series). For my pistols either 2 magazines full or 15 rounds for high-cap magazines. For my Garand, 2 clips full, or 16 rounds. For my Ruger bolt guns 2 magazines, for my .22 rimfires, a bunch. For my single shot guns, mebbe 10-12 rounds. I figger the more I shoot the less of "me" is shown in the groups by comparison. Besides, I like reloading and I like shooting so there ain't too many shots per group...

[Grizz]

if it goes 'ding' I hit it. if it doesn't go 'ding' I missed it.

can't get any easier than that.

when hunting, if it falls down, I hit it. if it runs off, I missed it.
(yeah, I might have to track it. that's a miss in my book)

simple
easy
and
consistent

[AJMD429]

Well, my thought on "shooting groups" is that you need a horizontal spreader on the muzzle of the shotgun.


Joe

Joe, you've come up with some good ones lately...!