Group consistency-advice-thoughts

[chkunz]

@chkunz, Theoretically, will ten 5 shot group aggs be smaller than 5 ten shot group aggs?

That is an excellent question!

Intuitively it seems like the AGG of ten 5 shot groups should be equivalent to the AGG of five 10 shot groups if we are shooting for score. For my load development I think I would be comfortable with combining two five shot groups to be equivalent to one ten shot group since I use mean radius rather than extreme spread for group analysis. I would definitely not combine based on extreme spread.

But you asked if they are theoretically equivalent and I am not sure how to rigorously analyze the two conditions. For example, when statistical analysis involves standard deviation the calculation of standard deviation involves N-1 in the calculation. For a large population of data, the N-1 has a very small effect but for a small number of data points it is more significant.

I will give this some more thought to see if I can give a better answer. I have several books on this subject and I am sure the answer is in there someplace. In the meantime, is there a statistician in the house that can answer this question?

 

[K22]

My daughter (biologist) should have a good understanding of statistics. I will ask her.
As I can already hear her sigh wondering where on earth to start, can you summarize what it is I'm looking for. I think I understand in a broad view but not how it would apply to such a small sampling like this.

It doesn't - statistically analysis is most effective on large sample sizes. Don't get bogged down with this issue. In fact, as I said, all you need to understand that there is inherent variation in all processes.

Let's discuss group size variation related issues. For the purpose of this discussion let's assume a quality rifle properly bedded and quality scope properly mounted.

1. Weather
2. Shooter variation - can be very significant
3. Variation from lot to lot of components including reloading procedures
4. Barrel condition relative to wear and cleaning
5. Type of rest used to produce groups and consistency in placing the rifle on rests
6. Shot sequence consistency (time between shots)

There are probably others, but these are the most significant that I'm familiar with. As you can see, there is an abundance of sources that can induce group variation. So, don't go pulling your hair out just yet. Take a deep breath, have a cold beer if you're so inclined.  The following is a possible solution.

Here's what I do, I decide what is the minimum on average of precision I need. For me, 1/2 moa + or - will meet all my varmint and predator hunting needs. Once I get a load that is repeatable at this approximate level testing off the bench with as stable as possible front and rear rests, I'm done with load development except to spot check when component lot changes and then only if I start to experience significant performance decline that I can't identify. Almost always, it's me.

The next phase is fine tuning the sight in and honing my skills in the manner in which I will use the rifle. For me, that's off shooting cross sticks. This is what I call, the performance phase and for me the most fun since I hate endless load development. The goal quite simply in to strive to keep all shots in the vital area at the distances I normally shoot or for a target shooter, the X / 10 ring. Select a target with scoring rings that reflects your goals.

The idea is to have fun, right? If you enjoy load development then have at it, me I'd rather be testing myself and skills in practical shooting situations. Different stokes for different folks.

PS: Keeping a shooting notebook to record the conditions and results each practical shooting session can be very helpful. Learn to call your shots and diagnose poor shots. You will soon start to be able to understand how weather is affecting your shots and you will start to refine your technique. Develop a mentality that every shot counts. Take your time and focus. This works - I've been doing it a long time. Good luck and good shooting.

 

[chkunz]

Keeping a shooting notebook to record the conditions and results each practical shooting session can be very helpful

This may be the most important point so far!

The more detail the better. But as a minimum, for each range event record what did you do, what worked, what did not work and what do you need to do next time. Notes made at the range are the best but the sooner the better. We start forgetting details as soon as we leave the range.