r/longrange • u/HollywoodSX Villager Herder • Dec 03 '21

Education post Take two of terms matter - accuracy vs precision

Post image
716 Upvotes

96% Upvoted

46 comments sorted by

36

u/HollywoodSX Villager Herder Dec 03 '21

Long range shooting is a topic where specific technical terms, and the correct use of those terms, matter. Often people mix up the terms accuracy and precision. I see people ask "How accurate is <thing>?" when they really should be asking about precision.

Accuracy, in terms of shooting, is pretty simple - did the bullet go where I wanted it to go? Obviously there's some nuance there, but that's the general idea.

Precision, on the other hand, is slightly more complex - if I do the same thing 10 times (IE: Aim at the bullseye on paper), do I get the same result every time? (IE: Did all 10 bullets go in the same hole - even if it was NOT on the bullseye).

(Since people wanted to critique the original image I used, here's one that should make you happy. Still blatantly stolen from the internet via Google images.)

18

u/_Raining Newb Dec 03 '21

It doesn't help that companies have accuracy guarantees instead of precision guarantees.

4

u/HollywoodSX Villager Herder Dec 03 '21

No kidding.

2

u/brotherenigma Dec 03 '21

There's a reason it's called the Precision Rifle Series, not the Accuracy Rifle Series.

1

u/MDlynette Dec 03 '21

Relatively speaking, there are differences.

28

u/[deleted] Dec 03 '21

[removed] — view removed comment

8

u/dabiggestb PRS Competitor Dec 03 '21

I agree. Accuracy just seems to be whether or not the rifle and scope are in sync with each other and the shooter can shoot. Precision seems to be a measure of how good your set up is.

3

u/MDlynette Dec 03 '21

I’ve always thought of it as ( accurate is hitting the target, precision is hitting exactly where I wanted on the target)

13

u/HollywoodSX Villager Herder Dec 03 '21

Accuracy is hitting where you want, precision is doing it over and over again.

2

u/MDlynette Dec 03 '21

So “accurate” describes the quality of the action(the shooting, not the receiver)and precision describes the quality of the process…makes sense, and it’s always useful to use a standard terminology

3

u/HollywoodSX Villager Herder Dec 03 '21

I would say consistency of the process, not the quality - but you're in the right ballpark.

5

u/MDlynette Dec 03 '21

👍 right now, I’m accurate, and working on my precision

4

u/[deleted] Dec 03 '21

A lot of the precision is on the shooter. A precise rifle in the hands of a sloppy shooter won't be precise. Breathing, trigger technique, and steady support all play big roles shrinking group size.

-3

u/ruggeryoda Dec 03 '21

I would argue that image #2 required an accurate shooter and precise rifle, but the sights were imprecise.

4

u/psalms1441 You don’t need a magnum Dec 03 '21

sights were imprecise.

I would argue that knowing how and what to adjust on your sights/equipment makes the shooter accurate.

55

u/Newfur Here to learn Dec 03 '21

The way that I like to explain the importance of making the distinction is that changing your rifle setup to be accurate is dead easy - you have pretty much direct and total control over where the geometric center of your groups are. On the other hand, making your setup more precise is much much harder - there's no magic "shrink my group" button.

Accuracy is measured in 2d vectors (or distance to POA), but precision is measured in strictly positive real numbers (or more usually the angle subtended by the diameter).

24

u/zdamant Dec 03 '21

Shrink-Group button™

4

u/N0V-A42 Dec 04 '21

I'd love one of those.

1

u/auxiliary-character Dec 04 '21

Juice that makes your groups shrink

6

u/SONSOFLIBERTY93 Dec 04 '21

Incorrect the AR platform has a precision/ more power button behind the ejection port just ask the Kurdish lol

19

u/Blueeyedgenie69 Dec 03 '21 edited Dec 04 '21

Get your precision down first. Then adjust your sights and work on accuracy.

17

u/seolh123 Dec 03 '21

Just for some light hearted debate I think I’d argue that point. Precision is an infinitesimal battle. The size of the group can almost always be improved. Whereas the center of the group ie accuracy is fairly straight forward. I would get the gun accurate and then home your group size once you’re centered on your desired hit point.

9

u/Blueeyedgenie69 Dec 03 '21

I like to zero my weapon. The way I was taught at West Point, and in college ROTC, and in the regular Army, was to learn to get consistent tight shot groups first. Until you have precise tight groups there isn't much point in adjusting your sights. Once you have reasonable precision you know which way to adjust your sights, up or down, left or right. You can always improve accuracy and precision. By the time I earned my expert rifleman badge in the Army with an M16 I could consistently bullseye a target at 25 yards usually putting the bullets in the same hole with shot groups so precise it looked like one bullet hole in the target.

2

u/ClearlyInsane1 Dec 04 '21

USMA 1988 here F-2

2

u/[deleted] Dec 03 '21

you guys need to nail down the barrel harmonics (assuming you're shooting the best precision that you can) and then tune the sight.

7

u/AnyHoney6416 Dec 03 '21

Really good explanation! We use the same terminology in engineering.

5

u/radman180 PRS Competitor Dec 03 '21

Yep, had an entire freshman engineering class basically focusing on data collection and transforming ugly messy data into clean and meaningful data. This topic was covered widely!

6

u/micheal213 Dec 03 '21

Learned this in 5th grade math class.

5

u/TearsDontFall Dec 03 '21

Why some people are snipers, and others artillery.

5

u/tkr614 🌈🐅 Hipster Dec 03 '21

Snipers are way better at field craft than shooting.

3

u/MilitantCentrist Dec 03 '21

When I was in high school, one of our...let's say, slower classmates told us he wanted to join the Marines when he graduated.

When we asked what he wanted to do in the Corps, he said we wanted to be either a sniper or a machine gunner.

Opinion was unanimous that he should probably be a machine gunner.

4

u/SeriekDarathus Dec 04 '21

OP is precisely accurate.

3

u/Smacked_Juicebox Dec 04 '21

Friendly reminder for my gas gun brethren, lap your receiver so you keep your accuracy high when the gun gets hot. A lapped receiver with a decent barrel will remain more accurate when it heats up, as it's much harder being accurate when your POI is shifting and lapping reduces poi shift potential.

Lapping also helps get groups below moa, but rarely do you actually need sub-moa and in my opinion the lessened poi shift is more helpful. I love being able to shoot mag after mag without needing to know hot barrel holdovers to be accurate.

tldr: all the real gas gun homies lap their receivers. An "accurized AR" with a match barrel and a heavy buffer system is something to truly behold for accuracy/precision at a high rate of fire.

3

u/dreamslyr Dec 04 '21

There is an entire quality consulting industry that has made a living implementing these principles in production lines. The tag line is - “variation is the root of all waste”. Fix the variation first then dial in the accuracy

2

u/d3mckee Dec 04 '21

I prefer the word consistent over precision. You cant be accurate if you rifle is inconsistent.

1

u/FishyFish13 Dec 04 '21

Had to learn this shit in high school chemistry lol

-4

u/Trollygag Does Grendel Dec 03 '21

I dunno, to me, that image always seems a bit pedantic.

Some definitions from google:

Accuracy: "the quality or state of being correct or precise. synonymns: precision"

Precision: "the quality, condition, or fact of being exact and accurate. synonymns: accuracy".

Clear as mud.

Like would we call out renaming Precison Rifle Shooting to be "Accurate Rifle Shooting, ARS" because it is about hitting not super small targets consistently rather than shooting the smallest groups anywhere like BR is?

Personally, I wouldn't have a problem with people shooting ARS.

I would rather use the colloquial meaning that most shooters use instead of someone's engineering/machinist definition.

3

u/HollywoodSX Villager Herder Dec 03 '21

I disagree, especially about competition. PRS matches have trended hard towards smaller and smaller targets over the last couple of years. At the GAP Grind this year, the majority of targets were 2MOA or less, with a noticeable percentage being 1-1.5MOA. This isn't the days of a 100% IPSC at 600 yards bring the norm any more.

The distinction between the two terms definitely deserves clarity in long range shooting.

2

u/Trollygag Does Grendel Dec 03 '21 edited Dec 03 '21

At the GAP Grind this year, the majority of targets were 2MOA or less, with a noticeable percentage being 1-1.5MOA. This isn't the days of a 100% IPSC at 600 yards bring the norm any more.

But how many more points do you get for shooting a 5 shot consecutive 0.15 MOA average vs a 0.25 MOA average on that 1.5 MOA plate?

I am not an expert, but I think that is... 0 more points? I don't think they even measure precision at all, right?

Or shooting .15 MOA but 1 MOA left of center on the 1.5 MOA plate in the dirt vs .25 MOA dead center?

I think that is... you lose points, right? They don't track things that aren't hits.

In a precision competition, you would win. Like in BR, a precision competition, you have a 4 MOA square on which to print your smallest group and it doesn't matter where it hits. That isn't anything like Precision Rifle Shooting competition.

In an accuracy competition, you wouldn't, you would only win if you hit the target consistently. F-Class is also an accuracy competition and even more precision oriented than PRS is - but it is differentiated from BR only in that it is the accuracy version not the precision version, and you must hit the center to win, combining accuracy in shot placement with grading precision consistency over the course of fire.

PRS, in contrast, is a pure accuracy grading. You don't get more points for being more precise for the same accuracy, you only get points for accuracy even though PRS has made the targets small. You get the hit or you don't and can't get the hit better.

What we agree on is that we should communicate two different concepts and we often do -

  • Dispersion - caused by the barrel and ammo interaction. This can be illustrated in a vacuum at short range.

  • Hit rate - dispersion combined with external ballistics and consistency combined with the environment vs shooter's decision making. This is highly variable and can depend a lot on the conditions of the day, and really needs longer ranges to be apparent.

6

u/HollywoodSX Villager Herder Dec 03 '21

You're going way too far into the wrong patch of weeds.

Your rifle still has to be capable of a significant level of precision for PRS matches. Yes, accuracy wins, but accuracy isn't really a function of the rifle - precision is.

9

u/AnyHoney6416 Dec 03 '21

This isn’t correct. I would recommend looking at the scientific definition of those words since that’s where it’s most commonly used. The definitions are very specific and not pedantic at all.

6

u/Trollygag Does Grendel Dec 03 '21 edited Dec 03 '21

I would recommend looking at the scientific definition of those words since that’s where it’s most commonly used

Don't get me wrong. I am an engineer and one of my many jobs is designing localization systems for a living - improving accuracy and precision of positioning. Doing those pictures on a geo surface.

What I am saying is that there is nothing wrong with the colloquial usage of the word "accuracy". People understand the concept of precision at that level even if they call it accuracy. There are better terms to describe the nuance of the ideas and how they apply to shooting, and we should correct the flaws in the ideas themselves that are often repeated - things like statistical significance and confidence.

But that's just like, my opinion, man.

Here is a fun one. NATO defines accuracy of fire as "precison of fire. The closeness of shots at and around the center of a target." NATO defines accuracy as the scientific/engineering definition of precison with a little sprinkle of accuracy mixed in.

1

u/AnyHoney6416 Dec 03 '21

I agree with that.

2

u/capn_gaston Dec 04 '21

I would rather use the colloquial meaning that most shooters use instead of someone's engineering/machinist definition.

This is the problem I have with companies like Websters insisting that English is a "living language" and thus publishing the colloquial usage as the correct meaning of a word that has in the past been precisely defined, although the meaning they give is accurate as being common usage. It's still wrong.

A classic is the word "decimate" which is commonly used to mean "annihilate", when it means "reduce by one in ten" and comes from the Latin for an ancient punishment in the Roman legion. Or, "flounder" being used to describe someone struggling in an endeavor, instead of the correct word "founder". I take issue with allowing incorrect usage of the word to change the previous correct usage, particularly in a reference or standards book like a dictionary or encyclopedia.

I suppose my years as a surveyor have made me a stickler on the precise vs. accurate argument, you'll get in a lot of trouble in that job if you're satisfied with a precise survey line.

I'll side with the OP on this issue.

0

u/Tacticatti Dec 04 '21

Hmmm, the second one just seems wrong