Group consistency-advice-thoughts

[Sleepyhollow]

How often are you cleaning your barrel?

I was gonna say powder fowling if all powder not being burned or table manners. Lots of variables to take into consideration here.

 

[K22]

I make a distinction between load testing versus a performance test and treat each differently.

The first thing I would do is remove the bipod then rerun the test with a high-quality front and rear rest IF you are attempting to measure the consistency of the load. I would want to eliminate as many shooting variables as possible when engaging in load testing. This same principle would apply to testing the rifle / scope combo.

On the other hand, since a bipod is apparently the way you use the rifle, these groups shot off the bipod are more of a performance test of the shooter and shooting aid (i.e., bipod). Both are important and have value but to my way of thinking are separate endeavors.

I shoot off a shooting sticks and do 95% of my range shooting off the sticks. However, before I can test my performance, I need to know that I have a rifle / load that is capable. So, I do load testing off the bench with a quality front and rear rest. Once I establish the load, I transition into performance shooting measuring me and my shooting aid (sticks).

To me, the variation shown in the groups posted are not at all unusual for performance testing reflecting shooter variation and the shooting aid used.

 

[jackieschmidt]

Factory barrel. Mass produced bullets.

Perhaps this the potential of the combination.

 

[Bronsin]

My Tikka showed a distinct preference for H4895, 45grs of it, and Sierra 150gr bullets. 2820fps from a 22" barrel. It did not care much for Hornady bullets and outside of varmint calibers, none of my other rifles ever did either.

 

[Doom]

The rounds are stringing vertically and I'm not sure how many rounds you've shot but I think the issue is shooter related. Especially if you have shot a fair number of rounds. Check your setup, especially around your rear bag. Monitor the recoil and see if you detect a difference in how the rifle reacts.

As others have noted this is a fairly low powered round but I wouldn't say they went to hell.

 

[Dog Breath]

What's causing you to think that's not statistical variation?

I meant to say that I have NO experience with statistical analysis of data.

 

[chkunz]

I make a distinction between load testing versus a performance test and treat each differently.

The first thing I would do is remove the bipod then rerun the test with a high-quality front and rear rest IF you are attempting to measure the consistency of the load. I would want to eliminate as many shooting variables as possible when engaging in load testing. This same principle would apply to testing the rifle / scope combo.

On the other hand, since a bipod is apparently the way you use the rifle, these groups shot off the bipod are more of a performance test of the shooter and shooting aid (i.e., bipod). Both are important and have value but to my way of thinking are separate endeavors.

I shoot off a shooting sticks and do 95% of my range shooting off the sticks. However, before I can test my performance, I need to know that I have a rifle / load that is capable. So, I do load testing off the bench with a quality front and rear rest. Once I establish the load, I transition into performance shooting measuring me and my shooting aid (sticks).

To me, the variation shown in the groups posted are not at all unusual for performance testing reflecting shooter variation and the shooting aid used.

This is consistent with my approach to load development for XTC. I do load development from a good bench rest with good bench rest procedure to determine the accuracy of the rifle and load. I shoot ten shot groups and multiple ten shot groups when I think I have identified a pet load. Then when I shoot the load in XTC competition I know that the points lost are on me and not the rifle and load.

 

[chkunz]

I meant to say that I have NO experience with statistical analysis of data.

Although a basic understanding of statistics and statistical analysis is helpful in group analysis, books on the subject are not easy to master. If you have a good high school or college background in math, give the subject a try or better yet find a friend that can teach you.

 

[Doug Casner]

Did you flinch the same on all groups? Doug

 

[K22]

I meant to say that I have NO experience with statistical analysis of data.

I do but it's really not necessary in my opinion for you understand all the technical aspects of this discipline. All you need to know is that there is variation in every process, even carefully controlled processes. The idea is to reduce the variation but you can never eliminate it totally.

 

[Dog Breath]

To me, the variation shown in the groups posted are not at all unusual for performance testing reflecting shooter variation and the shooting aid used.

The rounds are stringing vertically and I'm not sure how many rounds you've shot but I think the issue is shooter related. Especially if you have shot a fair number of rounds. Check your setup, especially around your rear bag. Monitor the recoil and see if you detect a difference in how the rifle reacts.

As others have noted this is a fairly low powered round but I would say they went to hell.

This is consistent with my approach to load development for XTC. I do load development from a good bench rest with good bench rest procedure to determine the accuracy of the rifle and load. I shoot ten shot groups and multiple ten shot groups when I think I have identified a pet load. Then when I shoot the load in XTC competition I know that the points lost are on me and not the rifle and load.

The consensus seems to be bench and shooter technique. I'm going to concentrate on those using the advice given.
Thanks people, I appreciate the help

 

[Dog Breath]

I do but it's really not necessary in my opinion for you understand all the technical aspects of this discipline. All you need to know is that there is variation in every process, even carefully controlled processes. The idea is to reduce the variation but you can never eliminate it totally.

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.

 

[chkunz]

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.

Start with the basics and do not try to get too deep but an understanding of standard deviation and variance which is simply the standard deviation squared and then learn about confidence limits, sometimes referred to as probability. The following might help.

In load development we frequently want to know if load A is more accurate than load B. Statistical analysis can help provide an answer to this question. The number of shots required for a meaningful answer depends on the statistical variance between A and B and the statistical confidence level that you choose. The smaller the variance between A and B the more data that is required for a meaningful answer. Also, the higher the statistical confidence level you desire the more data that is required. A statistical confidence level of 95 means that the probability is 95% that A is different than B but that also means that there is a 5% chance of being wrong. While a 98% confidence level has only a 2% chance of being wrong. The principles of statistics will guide you as to how much data you need to achieve your choice in confidence levels.

Although a basic understanding of statistics and statistical analysis is helpful in group analysis, books on the subject are not easy to master. If you have a good high school or college background in math, give the subject a try or better yet find a friend that can teach you.

I have done considerable load development for National Match Course competition (aka XTC). For load development for this application, I shoot 10 shot groups. I see where others doing load development for various applications report mostly using three, five or sometimes seven shot groups but rarely 10 shot groups. Their approach to load development may be appropriate for their application however using insufficient data for analysis for any application can lead to incorrect conclusions.

It has been shown that for long run averages 20 shot groups can be expected to average 1.79 times as large as three shot groups and 1.45 times as large as five shot groups but only 1.17 times as large as 10 shot groups, therefore, I choose 10 shot test groups for XTC load development.

While shooting XTC load development groups, I have observed the hits as the groups develop and sometimes the first three shots are very close together but after all 10 shots are fired the group is usually just another average 10 shot group for that load. Sometimes this is true for the first five shots as well but not as often as for three shots as would be expected. I think this supports my decision to go with the 10 shot test groups rather than three or five shot test groups.

There is also a tendency to throw out “flyers” when firing groups for accuracy testing. Sometimes I see wide shots that at first look like flyers but after the 10 shot group is in place many times the flyer no longer looks as much out of place. So, I do not ever throw out any flyers. Once I think I have a pet load defined, I shoot multiple ten shot groups with that load and average them and then if any wide shots are indeed not representative of the load, they do not play a significant role in analysis and decisions.

I calculate group size using the “extreme spread” method and also the “mean radius” method. The mean radius calculation values all shots in the test group on an equal basis as opposed to extreme spread which only values the two extreme shots. Extreme spread is more widely used for group analysis, but mean radius is a superior measure of merit and has significant advantages such as reducing the significance of a potential flyer.

 

[Ccrider]

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

 

[Dog Breath]

Start with the basics and do not try to get too deep but an understanding of standard deviation and variance which is simply the standard deviation squared and then learn about confidence limits, sometimes referred to as probability. The following might help.

In load development we frequently want to know if load A is more accurate than load B. Statistical analysis can help provide an answer to this question. The number of shots required for a meaningful answer depends on the statistical variance between A and B and the statistical confidence level that you choose. The smaller the variance between A and B the more data that is required for a meaningful answer. Also, the higher the statistical confidence level you desire the more data that is required. A statistical confidence level of 95 means that the probability is 95% that A is different than B but that also means that there is a 5% chance of being wrong. While a 98% confidence level has only a 2% chance of being wrong. The principles of statistics will guide you as to how much data you need to achieve your choice in confidence levels.

Although a basic understanding of statistics and statistical analysis is helpful in group analysis, books on the subject are not easy to master. If you have a good high school or college background in math, give the subject a try or better yet find a friend that can teach you.

I have done considerable load development for National Match Course competition (aka XTC). For load development for this application, I shoot 10 shot groups. I see where others doing load development for various applications report mostly using three, five or sometimes seven shot groups but rarely 10 shot groups. Their approach to load development may be appropriate for their application however using insufficient data for analysis for any application can lead to incorrect conclusions.

It has been shown that for long run averages 20 shot groups can be expected to average 1.79 times as large as three shot groups and 1.45 times as large as five shot groups but only 1.17 times as large as 10 shot groups, therefore, I choose 10 shot test groups for XTC load development.

While shooting XTC load development groups, I have observed the hits as the groups develop and sometimes the first three shots are very close together but after all 10 shots are fired the group is usually just another average 10 shot group for that load. Sometimes this is true for the first five shots as well but not as often as for three shots as would be expected. I think this supports my decision to go with the 10 shot test groups rather than three or five shot test groups.

There is also a tendency to throw out “flyers” when firing groups for accuracy testing. Sometimes I see wide shots that at first look like flyers but after the 10 shot group is in place many times the flyer no longer looks as much out of place. So, I do not ever throw out any flyers. Once I think I have a pet load defined, I shoot multiple ten shot groups with that load and average them and then if any wide shots are indeed not representative of the load, they do not play a significant role in analysis and decisions.

I calculate group size using the “extreme spread” method and also the “mean radius” method. The mean radius calculation values all shots in the test group on an equal basis as opposed to extreme spread which only values the two extreme shots. Extreme spread is more widely used for group analysis, but mean radius is a superior measure of merit and has significant advantages such as reducing the significance of a potential flyer.

Thank You! Very good explanation. I'm going explore this.

 

[joshb]

I’m thinking shooter fatigue. Ten minutes between groups x 14 groups? You’re in your second hour of shooting + 20 minutes or so? I’m ready for nap time at that point.......almost!

 

[Ccrider]

I’m thinking shooter fatigue. Ten minutes between groups x 14 groups? You’re in your second hour of shooting + 20 minutes or so? I’m ready for nap time at that point.......almost!

Surely you are taking breaks, drinking coffee, eating donuts and cleaning the barrel.

 

[6MMsteve]

if it's a factory barrel screw it off and stick in a B or B or ABC Kruger and you may have some better results, I would not expect anything from factory barrel, although some have shot great, if I want bugholes I'm going for a B or B or one of the custom barrel makers jmho it gets boring, it's more fun to wonder why

 

[Dog Breath]

I’m thinking shooter fatigue. Ten minutes between groups x 14 groups? You’re in your second hour of shooting + 20 minutes or so? I’m ready for nap time at that point.......almost!

Maybe but it's pretty relaxed. Settle in, take 3 shots, go have a look through the spotting scope, grunt(positive) or grunt(negative), 10 steps to the shack, let the dog out, weight powder and seat 3 rounds, call the dog back into the shack, settle in...

 

[Dog Breath]

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

After reading chkunz explanation I'm thinking aggregating all 50 shots no matter the group sizing. Treat them as one group?