Groups, Accuracy, and Statistics

[jmorris]

I constantly read things on this forum pertaining to the accuracy of rifles, whatever your definition of accuracy is. Most are referring to their rifles as being accurate because they can shoot an X size group. Rarely in such posts is the X size group actually defined. Is the X size group 1 shot, or 20? At what range? Is this group size consistent over a number of groups shot, or was it one group?

I have noticed this for years in many areas qualitative words used in areas better suited for quantitative values.

“I want an accurate rifle.”
“I want a more accurate rifle.”
“What’s more accurate and no, I don’t want to know by how much they differ.”

By definition a group is a number of things gathered, so 1 can’t be a group but 2 can. Many use 3, some use 5, fewer use 10. Only people gathering more accurate statistical data, shoot more than that.

I kind of figured the lack of definition allows for flexibility in interpretation (why politicians ALWAYS use qualitative words). Any one can say I want or have a super duper accurate firearm and if there is no set definition of what that is, they can be right or at least happy.

You could be flip side of ambiguous and are the guy that wants “the most accurate” firearm and your search is never ending. Pursuit should be where your happiness comes from.

Or you are a quantitative person that sets needs, wants and measures results using numbers. You wouldn’t tell a pharmacist to put “enough” or “a little more” of any ingredient into medicine. Tell a cook they needed to have the oven, “pretty hot” and cook it “quite a bit”or a machinist “precise”. You will never have a “standard” that everyone agrees on.

That said, we really don’t have universal agreement in quantification everywhere. There are lots of people in the world that wouldn’t know what you were talking about if you told them you were shooting 1 3/4 inch groups, at 69 degrees Fahrenheit, 2,300 feet elevation. Without converting to units of measure they understand.

 

[mcb]

I think a lot of us can put fairly specific quantitative numbers on what we would define as a sufficiently accurate and precise for a firearm. Most of those same people would have very different numbers depending on the firearm and its application. I have very different precision and accuracy expectations for my NRL22 rifle compared to my hunting rifles compared to my USPSA handguns.

 

[JFrank]

Everyone wants, claims and describes accuracy and precision a little differently but to be honest , sometimes it takes going to a race track to realize that the souped up factory hot rod isn’t really fast at all.
Benchrest accuracy is a different level again where short range groups are dominated by 6 ppcs shooting in the 1 or 2s for entire weekend only to finish 60th.
LR Benchrest again boggles the mind how a shooter could put 5 rounds just over an inch into a target a thousand yards away or average 4.5 inch groups for 12 targets over six months time.
Hunting rifles or Varmint rifles can be accurate but at a different level.

 

[jmorris]

I think a lot of us can put fairly specific quantitative numbers on what we would define as a sufficiently accurate and precise for a firearm.

For what?

 

[jmorris]

Hunting rifles or Varmint rifles can be accurate but at a different level.

Yes, that is the qualitative part of “accurate”, accurate to what unit?

People that have a benchrest mind see “accurate” as 1’s 2’s

People that have hunting rifle mind see “accurate” as being capable of killing deer everytime at usual to them distances.

Some pistol mind guys see “accurate” as A zone at 25 yards.

Never any Standard created.

 

[Seedy Character]

Tell a machinist, you need a rod that is straight, smooth and round.

He will answer, HOW straight, HOW smooth, HOW round? Then tell you, HOW much that costs.

I had a huge argument with our office manager.
We were our of state, on a calibration job. Each day, I sent them calibration data sheets to the office, to be put in binders.
The office manager decided the sheets should be computer printed, instead of hand written.
To make them pretty and uniform, since SOME of the data sheets were reported to .0001, them EVERY data point should be to .0001.

Testing a meter for MTV, accuracy can obtained to .0001.
Testing a 100 psi dial gauge, marked on 5 psi increments, CANNOT be reported as 20.0000.

Are your groups at 100 yards? Are they at 100.0000 yards? Huge difference

 

[HowieG]

I just got back from shooting two ten round test ladders with my Cooper M54. I'll post the data in a bit when I get my act together, and we can take a look.

View attachment 1053634

 

[HowieG]

All right, let me get this data out. Here are the prelims. The rifle is a Cooper M54 22-250 with a 22 inch barrel, 1 in 14 twist. The altitude at that spot is around 4900 feet. The temp was 43 F approx. Light gusty breeze about 3 mph I would guess. The two test ladders were built using RP brass, previously fired and freshly annealed, but not run through a sizing die post annealing. The powder was IMR 4064 because I have a fair amount of it. The charge was increased by 0.2 grains per charge up to just short of max per the Hornady and Sierra data. The bullets tested are the 55 Hornady VMAX (flat base) and the Sierra 50 grain Blitz King.

Let me say right off the bat that I was firing a test for data and was NOT SHOOTING FOR GROUP. My target was at 100 yards and I did use and aiming point for each test just to keep things over the chrono, but I was not concentrating really hard on obtaining a group. That wasn't the mission. That being said, I am attaching pics of the shot clusters because I do look at them to see if the bullets really are clustering or scattering.

The squares on the target are 1 inch.
View attachment 1053636 View attachment 1053637

The velocities for the VMAX load were: 3246, 3267, 3330, 3380, 3357, 3379, 3362, 3415, 3138 (no idea what happened), and 3425.

The velocities for the SBK load were: 3469, 3483, 3481, 3506, 3509, 3493, 3558, 3639, 3577, and 3726.

Opinions?

 

[HowieG]

Tell a machinist, you need a rod that is straight, smooth and round.

He will answer, HOW straight, HOW smooth, HOW round? Then tell you, HOW much that costs.

I had a huge argument with our office manager.
We were our of state, on a calibration job. Each day, I sent them calibration data sheets to the office, to be put in binders.
The office manager decided the sheets should be computer printed, instead of hand written.
To make them pretty and uniform, since SOME of the data sheets were reported to .0001, them EVERY data point should be to .0001.

Testing a meter for MTV, accuracy can obtained to .0001.
Testing a 100 psi dial gauge, marked on 5 psi increments, CANNOT be reported as 20.0000.

Are your groups at 100 yards? Are they at 100.0000 yards? Huge difference

I shot my test ladders today at a target 100.00000000 yards away, plus or minus a yard or two, kinda, sorta.

 

[AJC1]

I shot my test ladders today at a target 100.00000000 yards away, plus or minus a yard or two, kinda, sorta.

Only if verified by lazer and micrometer.

 

[HowieG]

Only if verified by lazer and micrometer.

My laser has a tolerance of +/- 1 yard.

 

[JFrank]

All right, let me get this data out. Here are the prelims. The rifle is a Cooper M54 22-250 with a 22 inch barrel, 1 in 14 twist. The altitude at that spot is around 4900 feet. The temp was 43 F approx. Light gusty breeze about 3 mph I would guess. The two test ladders were built using RP brass, previously fired and freshly annealed, but not run through a sizing die post annealing. The powder was IMR 4064 because I have a fair amount of it. The charge was increased by 0.2 grains per charge up to just short of max per the Hornady and Sierra data. The bullets tested are the 55 Hornady VMAX (flat base) and the Sierra 50 grain Blitz King.

Let me say right off the bat that I was firing a test for data and was NOT SHOOTING FOR GROUP. My target was at 100 yards and I did use and aiming point for each test just to keep things over the chrono, but I was not concentrating really hard on obtaining a group. That wasn't the mission. That being said, I am attaching pics of the shot clusters because I do look at them to see if the bullets really are clustering or scattering.

The squares on the target are 1 inch.
View attachment 1053636 View attachment 1053637

The velocities for the VMAX load were: 3246, 3267, 3330, 3380, 3357, 3379, 3362, 3415, 3138 (no idea what happened), and 3425.

The velocities for the SBK load were: 3469, 3483, 3481, 3506, 3509, 3493, 3558, 3639, 3577, and 3726.

Opinions?

You didn’t record each shot as it impacted the target…so you only have speed

 

[HowieG]

You didn’t record each shot as it impacted the target…so you only have speed

All I wanted was speed.

 

[JFrank]

All I wanted was speed.

Judging strictly on speed which load are you looking at ?
On the SBK target did you catch which round was the low shot ?

 

[HowieG]

Judging strictly on speed which load are you looking at ?

Speed is the main thing. Since I was looking at two bullets, I was also glancing at how each clustered up. The Sierra did that better than the Hornady, which didn't surprise me at all since that is usually how it works out for me. I think Sierra makes a bit better bullet. Probably why they cost more.

Anyway, I graph the speeds and look at the plateaus and dips if there are any. And how wide they are. Then I decide how I want to proceed. In this case I would first choose the Sierra bullet for a further look. If I was actually going to use this set of speed data, and I didn't want a really fast load, I would probably load for five round test batches at 3482, 3507-8 and shoot for groups.

In reality, I'm discarding this set of data because I got out of the house with a marginal 9 volt battery. Marginal as in low. I shot anyway just cause and was surprised when I didn't get an error message. When I tested that battery when I got home, it was at 7.9 volts. So, let's just say I have low confidence in that data.

 

[JFrank]

Pretty hard to go wrong with Sierras’s , they just make a good bullet.
Too bad you didn’t chart the hits on a separate target at you bench. That always adds a layer of interest to the discussion.

 

[Varminterror]

Throughout the first page, all I read was sour grapes…

Throughout the second page, all I read was absolute BS posted by one character in particular…

“Only the first shot matters,” “what’s the point of tiny groups if they aren’t centered on target?” “Shooting one group, one time doesn’t represent ‘normal’,” “100 yard groups don’t matter at 1,000 yards,”…

SMH… Go shoot your rifles…

 

[HowieG]

Pretty hard to go wrong with Sierras’s , they just make a good bullet.
Too bad you didn’t chart the hits on a separate target at you bench. That always adds a layer of interest to the discussion.

I can't do it with that rifle. I can't see those 22 caliber holes through that 3-9x40mm scope. I mostly can with my varmint rifle because it has more optics horsepower. Walking there and back every round for 10 rounds gives you 2000 yards of exercise but isn't conducive to steady shooting. I probably need to get a spotting scope, or a gopro to put downrange, but it isn't that important to me. In this case, with that Sierra Blitz King, six went through one ragged hole with a seventh right there touching, and three outliers. Pretty good odds for finding an accurate load out of that.

It just so happens that the bullet Cooper used to test that rifle is the Sierra Blitz King. My usual favorite bullet for that gun is the 52 grain Sierra Match King. So far, it doesn't particularly care for Hornady bullets. Doesn't hate them but doesn't love them either. A pity, because it's easier to find the Hornady bullets right now. They seem to outproduce everybody else.

 

[HowieG]

The main reason I am messing around with it right now, is that I have a lot more IMR 4064 than my normal powder, H380.

 

[jmorris]

I guess a lot of threads would be shorter. Would wind up with, one good post by the OP that had all of the facts and information gathered and written down as a concise report using the notes he took and a couple thanks for posting.

The way we have it now, we can add pages to threads pulling those details out piece by piece.

 

[HowieG]

I guess a lot of threads would be shorter. Would wind up with, one good post by the OP that had all of the facts and information gathered and written down as a concise report using the notes he took and a couple thanks for posting.

The way we have it now, we can add pages to threads pulling those details out piece by piece.

I think a forum provides an environment for likeminded people to talk about their interests with other likeminded people. If the intent was to provide concise information, an ordinary data website would suffice, and there are many of those. I think a lot of us are here because we don't have anybody around us to discuss these things with. There are things discussed at length on Highroad that would make an ordinary gunowner's eye's glass over. I certainly can't have a beer with six other people here locally and have a serious discussion about primers, but I can on the Highroad. Except for the beer part that is. I can sit here with a cocktail though. Hopefully others are doing the same thing.

 

[Show Me]

Depends on the application. My hunting guns the most important shot is the 1st one. Light guns with pencil barrels heat up fast, after 2-3 shots they start opening up. For my hunting rifle I want cold bore 1 shot accuracy. Very seldom do you get a second shot or need one.

For bench guns, like said repeatability over a broad range, and tightest grouping possible. I shrive for sub moa on the vertical axis, when working up loads. Knowing the wind can greatly effect bullet flight. I also know the person behind the trigger has a greater input than most realize.

My Henry long ranger 308. More than 2 shots is a waste of time and ammo. Shoot,mow the yard,repeat

 

[jmorris]

I think a forum provides an environment for likeminded people to talk about their interests with other likeminded people. If the intent was to provide concise information, an ordinary data website would suffice, and there are many of those. I think a lot of us are here because we don't have anybody around us to discuss these things with. There are things discussed at length on Highroad that would make an ordinary gunowner's eye's glass over. I certainly can't have a beer with six other people here locally and have a serious discussion about primers, but I can on the Highroad. Except for the beer part that is. I can sit here with a cocktail though. Hopefully others are doing the same thing.

I could think of no better way to honor the drift of your thread than to ask you what cocktail you are partaking in?

Only half joking, we are all here for fun.

 

[Show Me]

I think a forum provides an environment for likeminded people to talk about their interests with other likeminded people. If the intent was to provide concise information, an ordinary data website would suffice, and there are many of those. I think a lot of us are here because we don't have anybody around us to discuss these things with. There are things discussed at length on Highroad that would make an ordinary gunowner's eye's glass over. I certainly can't have a beer with six other people here locally and have a serious discussion about primers, but I can on the Highroad. Except for the beer part that is. I can sit here with a cocktail though. Hopefully others are doing the same thing.

Good bunch here except for the arrogant ones

 

[CQB45ACP]

Everyone wants, claims and describes accuracy and precision a little differently but to be honest , sometimes it takes going to a race track to realize that the souped up factory hot rod isn’t really fast at all.
Benchrest accuracy is a different level again where short range groups are dominated by 6 ppcs shooting in the 1 or 2s for entire weekend only to finish 60th.
LR Benchrest again boggles the mind how a shooter could put 5 rounds just over an inch into a target a thousand yards away or average 4.5 inch groups for 12 targets over six months time.
Hunting rifles or Varmint rifles can be accurate but at a different level.

Since you’re discussing precision of various types, let me quibble with your use of the terms “souped up factory hot rod.” A hot rod does not come from the factory. A hot rod results from a factory stock car being souped up. Souping up a hot rod would be redundant. I just wanted to contribute to this amazing thread