Groups are to small

[Bullgator]

So I watched the podcast by Hornady titled your groups are to small today. So I had about 80 rounds of new Gun Werks brass loaded that needed shooting so I shot a 80 shot string at 300 yards . My ES was 137.9 fps. and my SD was 36.7 average feet per second was 3309.7 .
With my Horizon 22creedmoor my question is what should I expect them to be and does it really matter as long as my group was good ? Which is another question what is considered a good group at 300 yards for a old one eyed man?

 

[JR1200W3]

Well, 3" would be 1 moa. 1.5" would be a half moa. I usually go for 1" groups at 300. I'm happy there but if I'm sub 1.5" I will begrudgingly take it.

If your groups are too small, try some Hornady bullets. That will probably fix the problem.

 

[supercorndogs]

E.S of 30-40 is pretty good

E.S of 100 pretty bad.

It depends on what you are doing with the rifle if it matters.

A point blank zero coyote rifle. Not much diffrence.

A rifle set up for shooting 700+ yards, you are gonna want to be in the pretty good category or batter. SD will give you better idea of likley dispersion vs E.S that can be effected by one large outlier.

 

[JR1200W3]

I'm taking a stats class right now. Distributions, Standard Errors, Confidence Intervals, inference, Hypothesis testing, etc. As I'm taking this class, all these discussions about SDs and ES keep invading my thoughts.

Something experienced shooters have learned intuitively is that the more rounds you fire as you're chrono'ing helps your SD's settle down over time. A lot of your variations in sampling will happen in the beginning. The first 5, 10, or even 20 rounds. But after 20 or 30, more rounds will actually help your SDs look better. This is due to the law of large sample sizes. And how Normal distributions solidify over larger samples. A larger sample creates a more accurate and narrower CI on the normal distribution. Now maybe not with your range, ES. But in terms of SD, you can get the bulk of your variation pretty soon.

 

[secondofangle2]

Well, because hardly anybody ever shoots 80 shot groups at 300 yards, it’s difficult to know. My wild guess is that 3MOA, 80 shot group even if you exclude five or 10 outliers would be pretty damn good.

Same thing with standard deviation: the habit of the entire gun community is to do repeated trials with tiny sample sizes and then hand pick the best ones to place in their mind or online as representative of their group size or standard deviation.

If people recorded mean radius of every single shot out of their gun as well as standard deviation, we would get a better (and BIGGER ) picture of reality.

Having said that a standard deviation of 36 seems pretty high

Also, did you realize you burned up 10% of your 22 Creedmoor barrel with this little test?

 

[Ledzep]

Long term repeatable SD:

Best: Single digit, 5-9fps (rare to see <8fps for a true SD over a large sample, but occasionally happens)
Good/Common: 10-15fps
Okayish: <20fps

Group Size
Best I've seen floats around 0.5-0.6 MOA
Common for PRS style rifles is 0.6-1.2 MOA
Thin profile and light weight rifles are more subject to heat and shooter fundamentals, 1.5-3 MOA can be common.

Regardless of what the weak point is (shooter, barrel, optic, ammo, heat, etc.), the point we're trying to get across is that when you combine it all and shoot a large sample test, you know what the entire system is capable of, and you can adjust max range engagement for acceptable hit probability accordingly.

 

[Harman117]

Take a picture and post it! Let's see that 80 round group

 

[straightshooter1]

So I watched the podcast by Hornady titled your groups are to small today. So I had about 80 rounds of new Gun Werks brass loaded that needed shooting so I shot a 80 shot string at 300 yards . My ES was 137.9 fps. and my SD was 36.7 average feet per second was 3309.7 .
With my Horizon 22creedmoor my question is what should I expect them to be and does it really matter as long as my group was good ? Which is another question what is considered a good group at 300 yards for a old one eyed man?

So, what did you group measure that you got at 300 yds.?

At 300 yds. I'd consider a "good group" to be ~1.5" or less.

An ES of 138 and an SD of 36.7 is pretty bad, in my book. I once had an 50 shot ES of 97 with an SD of 33 when testing a new primer. That was the worst I've ever gotten. When fire forming some new Alpha brass, 80 shots gave me an ES of 29 with an SD of 6.2 that produced .418 MOA group ( this being out of a .308 Ruger Precision Rifle, but with a Krieger barrel). Typically my high round counts yield SD's in the single digits. The factory ammo (mostly match grade) I've fired has yielded SD in the mid teens and ES's no worse than 50.

Hope this gives you some perspective. . .???

 

[JaoeyP]

So I watched the podcast by Hornady titled your groups are to small today. So I had about 80 rounds of new Gun Werks brass loaded that needed shooting so I shot a 80 shot string at 300 yards . My ES was 137.9 fps. and my SD was 36.7 average feet per second was 3309.7 .
With my Horizon 22creedmoor my question is what should I expect them to be and does it really matter as long as my group was good ? Which is another question what is considered a good group at 300 yards for a old one eyed man?

Was this a new barrel?

 

[RegionRat]

A suggestion for a different way of judging your shooting performance when you are shooting long strings at 300 yards (or any other standard known distance) is to just use a standard target and score it.

For example, highpower with a sling, or F-Class from rests, can use a standard 300 yard target and then you would be able to say if your score was High Master, Master, etc.. The F-Class 10 ring at 300 yards is 2.85" and the X ring is 1.42".

Not counting sighters, those games run 15 to 20 shot strings at 300 yards. A High Master runs a >97% score.
When those scores run into "clean" or 100%, then we go by X-count.

There are many folks who have "cleaned" the 300 yard line with all X during matches, but that is not seen at every match. Those are typically 3 strings of 20 shots.

So, the story changes based on if you are shooting with a sling, body support, versus from bag rests.

I don't know how heavy the bbl section runs on the Horizon 22 CM rigs, but if those bbls are not very heavy then the heat from extended strings will burn them up fast. I have 22 CM bbls cut three at a time and just don't worry about it, but I still keep the shots to say 5 at a time with time to cool off in between.

 

[nn8734]

I'm taking a stats class right now. Distributions, Standard Errors, Confidence Intervals, inference, Hypothesis testing, etc. As I'm taking this class, all these discussions about SDs and ES keep invading my thoughts.

Something experienced shooters have learned intuitively is that the more rounds you fire as you're chrono'ing helps your SD's settle down over time. A lot of your variations in sampling will happen in the beginning. The first 5, 10, or even 20 rounds. But after 20 or 30, more rounds will actually help your SDs look better. This is due to the law of large sample sizes. And how Normal distributions solidify over larger samples. A larger sample creates a more accurate and narrower CI on the normal distribution. Now maybe not with your range, ES. But in terms of SD, you can get the bulk of your variation pretty soon.

I had to take a few stats classes for my degree and you're learning the basics which def helps understand MV central tendency and dispersion data better. In my experience for any given centerfire rifle, SD starts out small (0-10 rounds where most people erroneously make their population attributions) then grows until it peaks around 20-25 rounds, give or take then begins to drop back towards a number that's more representative of the parent population, usually getting there by 30-40 rounds, as you say.

When I think Im ready to put a load into production, I'll do drop validation, firing 40-80 rounds of a given load receipe and record the entire string...My SDs in those cases are usually in the teens or low 20s for 5.56 and low-mid teens for .308, which is fine for my own requirements (hitting steel at 1000m and in)...I used to record my sessions only a two-three times a year as I hated carting out that LabRadar but now w/the little Garmin Xero, I record every single session (40-100 rnds).

 

[secondofangle2]

Good Lord, some of you guys shoot a heck of a lot more than I do. Three barrels at a time? Might as well go 4 at a time just like Perelli tires on a Porsche

 

[Baron23]

Good Lord, some of you guys shoot a heck of a lot more than I do. Three barrels at a time? Might as well go 4 at a time just like Perelli tires on a Porsche

What chu’ talking about, Jackson

 

[diggler1833]

I'm assuming the OP fired 80 rounds in a session with a built-for-hunting 22CM, and probably in some sort of hot environment with a moderate pace. The barrel's throat loves him.

Barrels are consumables, I'm not completely ignorant to that fact. However we learned that pretty quickly the OP would have seen some drastic ES and SDs... so this load is really only good for short-range use, even if accuracy was acceptable up close. So what was learned from say, 20 rounds to 80? I've only had SD get lower as the round count climbed over 10... not gone up (but it is possible with poor reloading habits I suppose).

*****

OP, sorry that your velocity was all over the place man. Since AFAIK, ADG makes Gunwerks' brass, I would consider it quality stuff. Even with virgin cases and clean necks, that velocity spread is problematic. If you don't mind sharing your equipment and procedures, some people in here might have some insight to help you out.

Regarding accuracy expectations, that depends on the rifle and purpose. I'm usually content if I can string 10 shots inside 1 MOA @ 300 yards consistently - meaning that I can repeat that group. Environmental factors are going to start impacting here as much as you and your load. Obviously if I do better, that makes me happier. If I shot F-Class, then I'd want to be like that with 20 shot strings.

One eye would make for slower time on target probably, but shouldn't affect your personal accuracy limitations.

 

[Ronws]

Take a picture and post it! Let's see that 80 round group

Reminds me of what I have learned here. Show us the paper or it didn't happen.

 

[Ronws]

@Bullgator

I have watched that and the follow-up and two associated videos, such as mean radius, at least 4 times, not kidding.

I learn something new each time.

Group the rifle for the job. Jayden even mentions this. For example, my activity is hunting, then 7 of the 3 round groups with cooling in between is going to be most germaine to what I do. Especially on the first shot. I may have to take a second shot. Hunters I know have never had to take a third shot. And I feel, as do others, if you are taking more than 3 shots at an animal, something is dreadfully wrong and you need to stop and fix whatever it is.

Also, I heard of a guy, Wade at Texas Predator Hunting (TPH Podcast) do a 5 shot group of one single cold bore shot each day for five days. The dispersion was the same as if he took 5 shots at once.

Also, when to group a rifle. Obviously after break-in. And clean when precision suffers. I would think 50 to 80 rounds should be sufficient.

As to the stats, those an academic interest, IMHO. What size is the group?

"The target doesn't lie." - Erik Cortina

But I have also known Cortina to say that if the rifle is not shooting 3/8" at 100 yards in the first 3 shots or so, he is not going to waste more time and ammo. If it is not doing it in the first few shots, 73 more is not going to make it better.

So, either by factory ammo that works or work up a handload that works and just stick with that.

I have watched Tom Rivers - Simple Living. He will work up a load for his hunting rifle. He is not even doing competitions. He just wants predictable precision for hunting. Granted, he is in the Southeast and the forests are thick.

 

[straightshooter1]

Good Lord, some of you guys shoot a heck of a lot more than I do. Three barrels at a time? Might as well go 4 at a time just like Perelli tires on a Porsche

How about 4 barrels at a time?

 

[JR1200W3]

I had to take a few stats classes for my degree and you're learning the basics which def helps understand MV central tendency and dispersion data better. In my experience for any given centerfire rifle, SD starts out small (0-10 rounds where most people erroneously make their population attributions) then grows until it peaks around 20-25 rounds, give or take then begins to drop back towards a number that's more representative of the parent population, usually getting there by 30-40 rounds, as you say.

When I think Im ready to put a load into production, I'll do drop validation, firing 40-80 rounds of a given load receipe and record the entire string...My SDs in those cases are usually in the teens or low 20s for 5.56 and low-mid teens for .308, which is fine for my own requirements (hitting steel at 1000m and in)...I used to record my sessions only a two-three times a year as I hated carting out that LabRadar but now w/the little Garmin Xero, I record every single session (40-100 rnds).

In clinical research it's common for studies to have small sample sizes and their results struggle to show a significant difference through a P value and Alpha. So Meta-analyses are used to aggregate independent comparisons and make an inference through a narrowed down confidence interval. Comparing the difference of means, Null and Alternative hypothesis, bootstrapping, T tests, and finally meta-analysis have consumed my last two weeks.

My wife has 20 years of experience in clinical research and a Doctorate in Microbiology so for the first time we can have a conversation about stats, lol. I was picking her brain about Meta-analysis this evening for an assignment and it occurred to me that one of the counter-arguments to the massive sample size argument is the value of reproducibility. Or the guys that say, "But every time I Chrono my five rounds groups I'm getting SDs under 8fps, so is a 30rd group really necessary?" Aggregating the SDs six individual 5 rd groups and demonstrating a consistent trend and tendency...that is reproducible has a ton of value. And it is a form of meta-analysis that is considered the gold standard in clinical research to deal with small sample studies.

I could see two sides to these arguments.

1. You need a larger sample size to have a better estimate of your average MV and SDs.

Or...

2. Everytime I shoot a five round group, my SDs are less than 10, over 6 shooting sessions.

With a 30rd group, all fired on one day, from one loading session, in A set of conditions.....even though you have a large sample size it doesn't mean that when you go out again and shoot another 30rd group that it's going to be reproducible. While if you can demonstrate reproducibility over multiple loading sessions, atmospheric conditions, etc....your meta-analysis of many small samples may have more value.

On the other hand, there's going to be a difference in means from multiple small samples, inevitably. Say you do shoot 6 x 5rd groups and your 6 different means are 2950, 2954, 2959, 2952, 2963, and 2945. You should be loading a summarized mean of means or the center of a 95% CI generated by those means into your Kestrel. Not just the last 5rd mean you shot. Whereas a 30rd group will greatly simplify the mean, as long as it's reporducible.

 

[nn8734]

1. You need a larger sample size to have a better estimate of your average MV and SDs.

I favor this argument. To me, it's more representative/indicative of how any random round or sample/subset of rounds in my entire prod lot is likely to behave on any given day.

Note that I am not saying it's the right answer - Im not qualified to tell you or anyone else what's right vs wrong when it comes to stats arguments. Just my opinion...

 

[JR1200W3]

I favor this argument. To me, it's more representative/indicative of how any random round or sample/subset of rounds in my entire prod lot is likely to behave on any given day.

Note that I am not saying it's the right answer - Im not qualified to tell you or anyone else what's right vs wrong when it comes to stats arguments. Just my opinion...

I think I'm going to load 30rds and shoot them at 100yds. Take photos of the group every 5rds. Then calculate the mean, SD, 95% CI for the total 30, and then do the same for the series of 5rd groups within the overall sample. And then randomize the 5rd mini-samples from the total 30rd population. See what the differences would be. I guess if my SDs and range is pretty tight, I won't see much difference. But it might be interesting to see if there is a difference between these two arguments.

 

[nn8734]

I think I'm going to load 30rds and shoot them at 100yds. Take photos of the group every 5rds. Then calculate the mean, SD, 95% CI for the total 30, and then do the same for the series of 5rd groups within the overall sample. And then randomize the 5rd mini-samples from the total 30rd population. See what the differences would be. I guess if my SDs and range is pretty tight, I won't see much difference. But it might be interesting to see if there is a difference between these two arguments.

Yea will be interesting if your mean of means in the series of five rounders is substantially different. It shouldnt be if both samples (30 rnd string and the series of five-round groups) are all shot in the same conditions, etc.

Will these rounds be factory ammo or your hand loads?

 

[JR1200W3]

Yea will be interesting if your mean of means in the series of five rounders is substantially different. It shouldnt be if both samples (30 rnd string and the series of five-round groups) are all shot in the same conditions, etc.

Will these rounds be factory ammo or your hand loads?

I don't really buy ammo. The most likely would be my 25GT. 37gr H4350, Alpha brass, 135 Hybrids. I get sub 8fps SDs everytime I shoot it. If I was thorough, I should probably do that gun and load, and then something that usually produces more variation. I took my SP-10 out today to see if I could get a beater load shooting halfway decent. Norma 130gr GTs, 42.5gr StaBall, Hornady brass, Ginex primers. I shot 3 x 5rd groups and a 10rd group. SDs were 19, 8, 5.7, and 19.

 

[nn8734]

I don't really buy ammo. The most likely would be my 25GT. 37gr H4350, Alpha brass, 135 Hybrids. I get sub 8fps SDs everytime I shoot it. If I was thorough, I should probably do that gun and load, and then something that usually produces more variation. I took my SP-10 out today to see if I could get a beater load shooting halfway decent. Norma 130gr GTs, 42.5gr StaBall, Hornady brass, Ginex primers. I shot 3 x 5rd groups and a 10rd group. SDs were 19, 8, 5.7, and 19.

I keep a small amt of factory ammo around for T/E purposes as well as to break in new barrels prior to load dev but beyond that, I load all my ammo.

My approach treats those sep groups as one and would avg the SDs and compute the range across all of those rounds...Testing both ways is fine - esp if you take a long break between samples and let the barrel cool each time. Maybe that would change MVs materially, maybe not - you will see when you do your testing...

 

[JR1200W3]

.Testing both ways is fine - esp if you take a long break between samples and let the barrel cool each time. Maybe that would change MVs materially, maybe not - you will see when you do your testing...

That's a good point. Any other tips to high round count testing? I don't normally do that. Could be helpful to know.

I watch Preston Moore's videos and always wonder how clean he's truly breaking those 30rds

 

[nn8734]

That's a good point. Any other tips to high round count testing? I don't normally do that. Could be helpful to know.

I watch Preston Moore's videos and always wonder how clean he's truly breaking those 30rds

Yes - dont focus on group size at 100m as it's only weakly correlated to MV consistency. In fact, I wouldnt shoot at 100m at all during these tests. Id do drop validation on steel at progressively further distances so you can kill two birds with one stone (gather mv test data to confirm/refute hypothesis and get some good dope on your ammo to see what it's doing at distance to record in your dope book). Will keep you focused on target vs group size which lots of folks get hung up on when also trying to get MV consistency data).

Do grouping drills separately where you're focused on one particular thing or another (ie zero shift at 100m when shooting prone vs off a tripod or barricade, etc).