Thread: 3 shot groups are useless!

Originally Posted by Tentman

I gave that to a cousin who was very desirious of its capabilities . . . .

Which were?

Originally Posted by Tahr

Which were?

I'm guessing those atributes were sub moa 10 shot groups
And a relative who gave it to him cheap / free with said sub moa load data

Originally Posted by gimp

In the Olympics Of Missing The Point, you boys would be gold and silver in the Long Jump Over Reading Comprehension

I thinik a good point here is that there is a world of difference between someone handloading building up loads and accuracy testing they may well need to shoot multiple groups - then there are hunters like me only use factory ammo so a check of zero may only be two shots

Originally Posted by Tahr

Which were?

Easy to shoot, well, and fast - nice balance might also describe it. Bear in mind I chopped 4" off a fairly heavy barrel. Aided by the fact that it can be top loaded into interchangeable magazines = lots of options for night shooting. Also integral pic rail for night vision.

Cozzys wouldn't know a 3 shot group even if it bit them, they just shoot grass thiefs!

That's dismaying news.

I lay prone with bipod and a bunched dog blanket under the heel of the stock.
Fired the bottom 3 shots. Stood up and had a pee. Fired the top 3 shots.

Sorry only 6 shots but Im not at home and conserving ammo. And no tape measure.

.223 M7 and 52 grn Targex.

What size are the sticky rectangles ?

Originally Posted by gimp

What size are the sticky rectangles ?

Look about .75"

Another 3 shots might have blown the whole thing apart.
I will still do the 10 shot thing when I get home.

On the short axis?

It does nicely demonstrate the variation you should expect with 3 shot groups in terms of the extreme spread - even with only 2 groups, they are quite different in size. You should expect variation of 70% +- from the average (if the average is determined over a meaningful number of 3 shot groups)

It is difficult to determine whether there is much of the expected variation in MPOI visible between these 2 groups (remember they are still a very small sample) without a reference dimension to measure against (e.g. grid paper)


More data needed to determine what it tells us about the MPOI or precision of this rifle system. Initial signs are that it isn't immediately obviously bad.

Originally Posted by gimp

It does nicely demonstrate the variation you should expect with 3 shot groups in terms of the extreme spread - even with only 2 groups, they are quite different in size. You should expect variation of 70% +- from the average (if the average is determined over a meaningful number of 3 shot groups)


More data needed to determine what it tells us about the MPOI or precision of this rifle system. Initial signs are that it isn't immediately obviously bad.

I truly thought the top group would be like the bottom one.

Originally Posted by Tahr

I truly thought the top group would be like the bottom one.

well technically....if the middle hole of top group was the aiming point/point rifle sighted in to hit...
and the bottom hole of bottom group was same
both groups have no other holes further away from point aimed at LOL.
one has two other holes slightly high..the other one slightly high and one slightly left...
statistician can make any data suit agenda

Originally Posted by Tahr

I truly thought the top group would be like the bottom one.

The idea that a rifle will group consistently the same size or mean point of impact with 3 shots is an unrealistic expectation - there will inherently be variation.

We can't get around the reality of statistics - it describes the nature of the world as it is (to a degree - all models are wrong, but some are useful).

The question is the degree of inconsistency, which obviously is dependent on the quality of the rifle/shooter system. No matter what, more data rather than less is required to confidently make statements about it. This is, of course, irrelevant for hunting at conventional ranges as our targets are large, results are rarely recorded and critically analysed, and precision is relatively unimportant compared to shooter proficiency (but shooters can waste a lot of time chasing unrealistic expectations based on insufficient data - gather more data initially and have more confidence, shoot less at paper and more at animals in the long run)


Rather than write a post about it myself, this article is reasonably good


https://www.bealeinnovations.com/stats-3shotgroup.pdf

interestingly neither group is larger than aiming point....eg put the holes over the black spot and both lots will fit..all be it the one inside and other cutting outside....

The problem I can see is all the stickers covering all the other bullet holes