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5 shot groups "kinda worthless"?

So to be reasonably sure a particular load works, how many rounds of that load are enough? I have loads that equal or better the best groups on the board repeatedly over the last 2 years. I have others I’ve abandoned because they were not repeatable. I’ve never had a load tighten up consistently.

If all those groups are potentially the same for long term accuracy, the only way to know is to keep shooting them.
 
My goal is to collect the best data I can with the least amount of shots at each tuning session. I see no good reason for shooting ten and twenty shot groups to qualify or confirm a component of disqualify a component, with all of the information resources available to a guy theses days it just doesn’t take that many shots, if so then I’d look for a new method of load development.
 
There's no point in shooting multiple groups with the same ammo. For example, if you're going to shoot 5 consecutive 5-shot groups with the same ammo, just shoot all 25 into one group. The dispersion of all 25 shots will tell you more than the average of five 5-shot groups.
 
fxvr5 said:
There's no point in shooting multiple groups with the same ammo. For example, if you're going to shoot 5 consecutive 5-shot groups with the same ammo, just shoot all 25 into one group. The dispersion of all 25 shots will tell you more than the average of five 5-shot groups.
Click to expand...

Short and long range Benchrest competition may be the most demanding discipline and world records are determined by 5 shot groups, we test in small samples to save barrels and bullets and compete in small groups. If we can trust small samples maybe others could too.
 
South Prairie Jim said:
Short and long range Benchrest competition may be the most demanding discipline and world records are determined by 5 shot groups, we test in small samples to save barrels and bullets and compete in small groups. If we can trust small samples maybe others could too.
Click to expand...

But aren't you talking about 5-shot groups with different ammo?
 
So y'all are saying if I shoot 5 random rounds out of a 50ct box, and three are darn near touching and two are flyers that I called, you don't consider that good enough? I do. I do not see any issue with doing my random 5 round groups. It's usually good enough for government work. Like I already posted pictures of my 5 round groups with my 6.5 PRC and y'all seem to ignore that. If 5 random rounds are that accurate out of a basic hunting rifle, then I'm going to stop doing load development and just run that exact recipe from now on.
 
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fxvr5 said:
There's no point in shooting multiple groups with the same ammo. For example, if you're going to shoot 5 consecutive 5-shot groups with the same ammo, just shoot all 25 into one group. The dispersion of all 25 shots will tell you more than the average of five 5-shot groups.
Click to expand...

This isn’t correct, and @denton discussed why already within the thread.
 
Outside of a few rifles, a 25 shot group is not going to tell you much, if you have to reload several times during that. Then factor in barrel heat and possible changes in the wind.
 
When I was shooting F class, the match was 20 shots plus sighters, usually two or three if you were well zeroed to start with.
So yes, 25 shots in a row is meaningful, if you do that sort of thing.
 
What about barrel heat up and shooter/visual fatigue?
Wider time window could allow more/other variability.

I shoot 5 shot groups. Has worked fine for me.
If I can shoot back to back groups of same size, am happy.
 
Jim Watson said:
When I was shooting F class, the match was 20 shots plus sighters, usually two or three if you were well zeroed to start with.
So yes, 25 shots in a row is meaningful, if you do that sort of thing.
Click to expand...
Did you test powder charges in 25 shot strings? Did you test each seating depth in 25 shot strings?
How about primer testing and neck tension testing, are all those in 25 shot each ?
Or did you use smaller samples for testing prior to simulating a full course of fire ?
Just curious as I’m not an F class shooter.
 
If you shoot a 25-shot group, how are you going to analyze the data? If you are just going to measure group size, you'll be throwing away most of the information contained in the data.

If you have the time to measure each shot's distance from group center and compute the standard deviation, then you preserve all the dispersion information in the data. That approach works, but is a bit of a burden.

Averaging 5 5-shot groups is a simpler approach and it preserves almost all the information content of the data.
 

You did not directly answer post #81.

Do you use random store bought ammo for Short and long range Benchrest competition?
 
denton said:
If you shoot a 25-shot group, how are you going to analyze the data? If you are just going to measure group size, you'll be throwing away most of the information contained in the data.

If you have the time to measure each shot's distance from group center and compute the standard deviation, then you preserve all the dispersion information in the data. That approach works, but is a bit of a burden.

Averaging 5 5-shot groups is a simpler approach and it preserves almost all the information content of the data.
Click to expand...

You don't need to 'analyze' the data. Just measure the spread. That's all that matters.

Rifle shooters can go nuts on analysis if they like, but the easiest way to see how a gun likes the ammo is to just measure the spread of all shots in one group. And you can see on the target immediately if it is prone to fliers.

Averaging 5 5-shot groups is a simpler approach. . . Really? That's simpler than just making one measurement?
 
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fxvr5 said:
You don't need to 'analyze' the data. Just measure the spread. That's all that matters.

Rifle shooters can go nuts on analysis if they like, but the easiest way to see how a gun likes the ammo is to just measure the spread of all shots in one group. And you can see on the target immediately if it is prone to fliers.

Averaging 5 5-shot groups is a simpler approach. . . Really? That's simpler than just making one measurement?
Click to expand...
Averaging 5 5-shot groups is simpler that measuring each shot and calculating standard deviation, which is what you have to do if you want all the information that the data holds.

Measuring a single 25-shot group discards much of the statistical strength of the data. Of course, shooting is fun, and you may enjoy shooting twice as many shots as you really need in order to get reliable information. That's up to you.
 
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fxvr5 said:
Do you use random store bought ammo for Short and long range Benchrest competition?
Click to expand...

I answer No to this question. Please restate your other question if you like and I’ll try and answer it if I can.
My thoughts on store ammunition all looking similar on paper at 100 yards are pretty basic in that a generic recipe is known, for example a 308 with 44.g of Imr 4064 under a 168 smk will shoot in most rifles and look decent at a hundred yards despite the name on the box but take those to a greater distance and the small details start to separate the brands such as one rifle might like 44.2 where another likes a bit less. Extra rounds won’t help me clairify results as well as moving back a couple hundred yards.
 
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As I struggle with my PTSD from Stats in college I am flashing on sample vs population stuff. Isn't this what we are talking about? So if population is barrel life shot count, what sample gives us the representative picture of all shots fired. Right? I'm sure its not that simple.

Seems easy enough to test. (or at least generate more questions) Buy a bunch of barrels, control the variables, and shoot them to death. Crunch the numbers and tell us how many rounds to shoot to get a picture. I'll bet it will be 50% of barrel life or better. So "kinda worthless" also.

Are we ever gonna get to the answer?
 
This is what happens when statisticians teach reloading.

Basically I want a load that puts all shots within a circle of a certain diameter. I don't care where they are in the circle, as long as they are all there. So, small ES is important to me. SD not so much.
And yes, I am well aware that I am basically only using 2 points of data of the multitudes available, but those are the only 2 points that matter to me.

What I do not want is a small SD and large ES. Large ES loses the match even if it is just 1 "flyer".

100-2X beats 99-9x any day of the week and more so on weekends.
 
JerkyFreak said:
This is what happens when statisticians teach reloading.

Basically I want a load that puts all shots within a circle of a certain diameter. I don't care where they are in the circle, as long as they are all there. So, small ES is important to me. SD not so much.
And yes, I am well aware that I am basically only using 2 points of data of the multitudes available, but those are the only 2 points that matter to me.

What I do not want is a small SD and large ES. Large ES loses the match even if it is just 1 "flyer".

100-2X beats 99-9x any day of the week and more so on weekends.
Click to expand...

Well, OK, but you do realize that if you remove "special cause" from the system, SD and ES are directly convertible to each other?
 
denton said:
Well, OK, but you do realize that if you remove "special cause" from the system, SD and ES are directly convertible to each other?
Click to expand...
No, they are not. ES is a measurement of 2 points the furtherest apart.
SD takes a mean of all points and then calculates the mean deviation from that mean (roughly speaking).

For instance, if the SD is roughly half of the ES, the points are quite widely distributed between those points. If the SD is around 1/4 of the ES, most of the points are grouped quite closely to the mean with a few outliers at the extreme ends.
 
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