5 Shot Groups VS 10 Shot Groups

[MarkS]

I have got into long range Rimfire in the last few years. My back ground is long range centerfire 600 and 1000yds benchrest. When working up loads for centerfire, I shoot multi 3 shot groups at 100 yds, to find the load I liked.Then I would go to 5 shot groups, then to 200yds. I feel 5 shot groups are testing Me and the gun.

Now that I am into Rimfire, I shoot multi 5 shot groups at 50 yds, when move to 100yds. I see guys shooting 10 shot groups, at 50 yds and 100yds. Would that be testing the shooter, more than the gun and ammo? Even with wind flags, and the Rimfire being so easly moved by the wind, how can you tell what is going on in your groups. Is it the ammo or did I miss a wind shift. I am lucky where I live, to get 5 shots off under the same condition, must less getting 10 shots.

I'm not knocking 10 shot groups. I am just asking, are 10 shot groups counterproductive, or is it what I should be doing?

Mark Schronce

 

[10/22AppleCreekShooter]

I will tell you that 10 shot groups are about 5 times tougher than 5 shot groups. I shoot 5 shot groups mostly. But I do enjoy tring to get 10 shots that are respectable groups.

 

[10/22AppleCreekShooter]

 

[Barrel Nut]

Check out the latest book by Bryan Litz. He devotes an entire chapter to this subject; i.e. how do three, five, and ten shot groups relate to one another and how do groups shot at 100 yards relate to those shot at 600 and 1000 yards........stuff like that. It's pretty good.

I keep all my testing data in Excel spread sheets. Using information I learned from his book, I developed correction factors so that I can compare various load recipes with one another even if the groups were shot at different distances and contained a different number of rounds.

In other words, I converted my all my oranges to apples so now I can compare apples-to-apples.

 

[patriot]

Prone shooters face 10 shot groups every 100 yard target.

 

[dmoran]

 

[spclark]

Why suddenly can't I 'like' DMORAN'S post?

I'm logged in yet I get told I don't have permission?

That's a new one....

BTW I LIKE that graph, why I stick w/5's when testing too. Otherwise it's 15 or 20 for when they ALL count!

 

[savagedasher]

I will bet you nobody has ever shot a smaller group then the second shot . Larry

 

[HuskerP7M8]

View attachment 1004020

Until the last couple of years the statistical efficiency or statistical correlation to precision based on the number of shots in a group used for testing has been calculated as being 7 shots per each group. Recent simulations using such as Excel's "Monte Carlo" with one million iterations has resulted in the chart "dmoran" posted.

I've always been interested in how the statistics I generate during testing translates to real world target scores. What I did was write algorithms based on the data I've gathered that most closely match the scores I've shot in my tunnel, the scores I've shot in indoor matches with little or no mirage, and the outdoor matches I've shot under near perfect conditions.

I could have written the algorithms without using any of my data because the means to do so are pretty well known. The only thing you really need is a specific circle diameter that the shot distribution lands in, or in this particular case the scoring ring diameters of the ARA target to predict potential scores based on which statistic you choose to use for that estimation.

A brief, and I hope, simplified explanation of the following charts is probably in order. It may not be simple enough for everyone except for "dmoran", but I've already said and will say some things that may horrify a real statistician. I'm sure they'll forgive me considering I'm just some hick in Nebraska pretending to be an expurt. LOL

All 3 charts use the same data from a single barrel utilizing the same 3,375 shots. I didn't look, but there's probably some 30 to 40 different lots of ammo in the data.

All 3 charts show the relationship or statistical correlation to real world scores (ARA Score/C'd) for testing results using 2-shot groups, 5-shot groups, and ATC (Average To Center) also known as MR (Mean Radius).

The red line thru the data points is a trend line and in this case it's a linear trend line. Excel calculates the best fit thru the data points and creates the line.

R2 is a calculation Excel uses to tell us how well the data fits the trend line. Higher numbers are better.

Correl is the term used in the Excel formula bar and is short for correlation. Whether minus or positive, the higher the number the closer the relationship or the higher the correlation is to predicted scores.

You should notice there is some scatter that prevents you from drawing an intersecting line from the group size average in the horizontal axis of the charts and predict an exact score. This scatter is perfectly normal and can only be lessened with the addition of more data. Considering this data is composed of 135 separate tests and 3,375 total rds, it should be obvious why scores, and or group ES's vary so much from target to target even under benign conditions with the same rifle and ammo.

The other important result to notice is how the prediction for real world scores suffers if for some reason you were to decide to use 2-shot groups in your testing. The same happens if you use anything other than groups with 5 to 6 shots in them. Testing using 2-shot, 3-shot, 10-shot groups, etc don't work well when testing ammo or evaluating rifle performance. Again, this is well known but probably unfamiliar to most of you.

There's a lot to digest here and I'm certain there will be disagreement. All I can do is present the data and let everyone draw their own conclusions.

Landy

2-Shot Correlation:

5-Shot Correlation:

Average To Center Correlation:

 

[Boyd L.]

I have got into long range Rimfire in the last few years. My back ground is long range centerfire 600 and 1000yds benchrest. When working up loads for centerfire, I shoot multi 3 shot groups at 100 yds, to find the load I liked.Then I would go to 5 shot groups, then to 200yds. I feel 5 shot groups are testing Me and the gun.

Now that I am into Rimfire, I shoot multi 5 shot groups at 50 yds, when move to 100yds. I see guys shooting 10 shot groups, at 50 yds and 100yds. Would that be testing the shooter, more than the gun and ammo? Even with wind flags, and the Rimfire being so easly moved by the wind, how can you tell what is going on in your groups. Is it the ammo or did I miss a wind shift. I am lucky where I live, to get 5 shots off under the same condition, must less getting 10 shots.

I'm not knocking 10 shot groups. I am just asking, are 10 shot groups counterproductive, or is it what I should be doing?

Mark Schronce

In my experience, 5 shot groups (using the ammo of my choice) is a reliable means to tell me if the combination of gun, ammo, and scope is capable of competing (Smallbore silhouette). The distance of testing is always at the most demanding distances. Usually that means longest, but not always.

In my humble and completely unscientific opinion, extended strings of fire would give more of a report of the shooter's ability to maintain high levels of concentration, and may be a great training tool for the silhouette, prone, 3-P, etc.... shooter. As you pointed out, the vageries of wind, and bullet B.C. remove much of the technical aspect of rimfire shooting from the menu of things to improve.

Love the statistical analyses and reporting methods.

 

[MarkS]

In my experience, 5 shot groups (using the ammo of my choice) is a reliable means to tell me if the combination of gun, ammo, and scope is capable of competing (Smallbore silhouette). The distance of testing is always at the most demanding distances. Usually that means longest, but not always.

In my humble and completely unscientific opinion, extended strings of fire would give more of a report of the shooter's ability to maintain high levels of concentration, and may be a great training tool for the silhouette, prone, 3-P, etc.... shooter. As you pointed out, the vageries of wind, and bullet B.C. remove much of the technical aspect of rimfire shooting from the menu of things to improve.

Love the statistical analyses and reporting methods.

Boyd,
I'm with you, 5 shot groups will cover anything I shoot. I am into long range steel match, shooting match sticks , spitting playing cards, hitting gumballs, and so on. http://forum.accurateshooter.com/threads/cz-455-out-today.3920266/
I would love to get to this match.
https://www.youtube.com/channel/UCzDSJ-eBsPCJl99XVN9Y79g

I need to know were that first round will hit.

Thanks, Guys for the input.
Mark Schronce

 

[spclark]

I need to know were that first round will hit.

Whaaat??

You mean to tell us there are matches that don't allow sighters?

And I already know about the CMP & their game plans thankyouverymuch.

Knowing where that very first round will hit - every time - is asking for a lot, don't you think?

 

[USMCDOC]

Whaaat??
Knowing where that very first round will hit - every time - is asking for a lot, don't you think?

He just wants to be Doug Marcaida, Jr! "I love the lines of this weapon, feel and finesse of the trigger, the bell curve of the bullets! It is a good job, these bullets will hit!

 

[MarkS]

Whaaat??

You mean to tell us there are matches that don't allow sighters?

And I already know about the CMP & their game plans thankyouverymuch.

Knowing where that very first round will hit - every time - is asking for a lot, don't you think?

Some will give you a sighters at the start, for the day, some do not. You can sight in at 25 or 50 yds, then have to click up out to 200 yds. I don't think I have ever got sighter for a silhouette match.
It is not going to be there every time, but close most if the time. I use a 50yd. zero, then know all of my dope. You will have to make adjustments on the fly.

Mark

 

[spclark]

It is not going to be there every time, but close most if the time.

A more realistic approach, one I take myself.

That 'Circle of Confusion' will be a source of endless frustration if you think for a moment you can make it smaller than probability allows.

 

[rcmark]

Watch this video:

 

[seymour fish]

I have got into long range Rimfire in the last few years. My back ground is long range centerfire 600 and 1000yds benchrest. When working up loads for centerfire, I shoot multi 3 shot groups at 100 yds, to find the load I liked.Then I would go to 5 shot groups, then to 200yds. I feel 5 shot groups are testing Me and the gun.

Now that I am into Rimfire, I shoot multi 5 shot groups at 50 yds, when move to 100yds. I see guys shooting 10 shot groups, at 50 yds and 100yds. Would that be testing the shooter, more than the gun and ammo? Even with wind flags, and the Rimfire being so easly moved by the wind, how can you tell what is going on in your groups. Is it the ammo or did I miss a wind shift. I am lucky where I live, to get 5 shots off under the same condition, must less getting 10 shots.

I'm not knocking 10 shot groups. I am just asking, are 10 shot groups counterproductive, or is it what I should be doing?

Mark Schronce

Mark, Stats don't begin to tell you what you need to know, which is how long a string can you run before needing to clean, defined as the point accuracy drops off. Your course of fire including number of slighter shots, number of shots per tat, etc, and your time available to clean between any relays or changes of distance set the necessary parameters. A reason to shoot a long string is to discover at what round count excess wax may accumulate and be blown out, yet coming right back in on call after throwing that one shot. Tends to be " fluky" with just one particular ammo/lube. Might happen every 15-20 rounds, but can burn you..you want to test in the wind, but take time and just shoot one condition to assess groups. If you get a tight little waterline at 100-200 you are in tune. Any ammo that gives a couple drop-outs per box, at random, not every x number of shots (think Wolf), but shoots tight otherwise, is ok practice, but won't win $$$. You have shot plenty to know if you missed a condition, so don't hold that against the gun, i.e. If the shot follows the wind predictably, you are golden. Seymour