How many shots in a group to sufficiently demonstrate precision?
- Thread starter Centercut
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ACCURACY s the ability to hit the aimpoint exactly. Group shooting doesn't really show accuracy per se, but rather, shows PRECISION. Precision is the ability to put shots repeatedly close to each other. Its possible for a gun to group well, but not put the center of groups repeatedly in the same aimpoint. Obviously, the shooter skill and weather conditions can and will affect both accuracy and precision, but technically, precision is more a function of the gun and ammo.
PRECISION is shown by shooting a group containing a statistically large number (over thirty) under ideal conditions with as few shooter-induced potential issues as possible. Accuracy is proven by repeatedly hitting aimpoints on the first shot. A combination of many groups of three to five shots can demonstrate accuracy and precision if all shots are very close to the aimpoint. I think ten groups of five shots is a good indicator of where you are at the moment.
Mike, the monthly matches we hold use a one shot per target format over long series of shots (75 record shots) to prove accuracy.
Since its natural to assume small groups at respectable distance means the gun and shooter are "accurate", its common to assume groups "prove" accuracy.
PRECISION is shown by shooting a group containing a statistically large number (over thirty) under ideal conditions with as few shooter-induced potential issues as possible. Accuracy is proven by repeatedly hitting aimpoints on the first shot. A combination of many groups of three to five shots can demonstrate accuracy and precision if all shots are very close to the aimpoint. I think ten groups of five shots is a good indicator of where you are at the moment.
Mike, the monthly matches we hold use a one shot per target format over long series of shots (75 record shots) to prove accuracy.
Since its natural to assume small groups at respectable distance means the gun and shooter are "accurate", its common to assume groups "prove" accuracy.
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Would you agree hard to have one without the other? I’ve never had a problem with a precise shooting gun being accurate but maybe I’m missing something. PUN INTENDED
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I can answer that. That’s God’s way to teach you humility. And not to swear
I think he has better ways to teach humility to those who can learn it.
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I agree with Therealld, precision is what mostly people on the forums mean when they talk about accuracy.
There is a really cool wikipedia on ballistics, especially on measuring the performance of both gun/equipment and of the shooter. It's called Ballistipedia!
The guys writing the Ballistipedia seem to be real cracks, they know their stuff, the statistics and all. They discuss accuracy vs. precision here:
http://ballistipedia.com/index.php?title=What_is_Precision%3F
After reading a lot of the articles one thing became clear: measuring group extreme spread really only measures 2 shots (the two farthest away, say 2 inches apart on a 100 yard shot), and we disregard the other shots completely (of a ten shot goup, 8 shots could be all bunched in a 1/2 inch hole -- but the two shots 2 inches apart mess up our "official group size" and do not consider the excellent grouping of the other 8 shots...!) Despite the fact that 2 shots would miss my quarry, the other 8 would be a head shot.
That gives me an 80% kill rate, not bad by my reckoning, but if we only declare that "we/the gun shoots only 2 inch groups" we wouldn't think that this we/the gun is actually excellent!
The Ballistipedia suggests not to measure group extreme spread but to use a measure that quantifies all shots of a group, not just the two worst ones. One of the measures they suggest is the group mean radius.
Without getting into details, there is an app out there ($11, no ads), that will scan target cards using the camera of your cell phone and calculate instantly your group mean radius (and extreme spread, and points) (your hits are automatically registered and scored).
The app webpage is called TargetScan, and their wepage is here: https://targetshootingapp.com
The app supports over 200 different target cards from all over the world (and you are limited to those): https://targetshootingapp.com/wiki/Supported_disciplines/
If you want to get a free version to calculate mean radius (and extreme spread) (and you will have to tap the screen to place each shot, this is not automatic in this app), here is RangeBuddy: https://play.google.com/store/apps/details?id=com.reloaderscloud.rangebuddy
An advantage: You can use any paper target (black dot on a legal pad works just as much as a commercially produces target card).
Happy shooting,
Matthias
There is a really cool wikipedia on ballistics, especially on measuring the performance of both gun/equipment and of the shooter. It's called Ballistipedia!
The guys writing the Ballistipedia seem to be real cracks, they know their stuff, the statistics and all. They discuss accuracy vs. precision here:
http://ballistipedia.com/index.php?title=What_is_Precision%3F
After reading a lot of the articles one thing became clear: measuring group extreme spread really only measures 2 shots (the two farthest away, say 2 inches apart on a 100 yard shot), and we disregard the other shots completely (of a ten shot goup, 8 shots could be all bunched in a 1/2 inch hole -- but the two shots 2 inches apart mess up our "official group size" and do not consider the excellent grouping of the other 8 shots...!) Despite the fact that 2 shots would miss my quarry, the other 8 would be a head shot.
That gives me an 80% kill rate, not bad by my reckoning, but if we only declare that "we/the gun shoots only 2 inch groups" we wouldn't think that this we/the gun is actually excellent!
The Ballistipedia suggests not to measure group extreme spread but to use a measure that quantifies all shots of a group, not just the two worst ones. One of the measures they suggest is the group mean radius.
Without getting into details, there is an app out there ($11, no ads), that will scan target cards using the camera of your cell phone and calculate instantly your group mean radius (and extreme spread, and points) (your hits are automatically registered and scored).
The app webpage is called TargetScan, and their wepage is here: https://targetshootingapp.com
The app supports over 200 different target cards from all over the world (and you are limited to those): https://targetshootingapp.com/wiki/Supported_disciplines/
If you want to get a free version to calculate mean radius (and extreme spread) (and you will have to tap the screen to place each shot, this is not automatic in this app), here is RangeBuddy: https://play.google.com/store/apps/details?id=com.reloaderscloud.rangebuddy
An advantage: You can use any paper target (black dot on a legal pad works just as much as a commercially produces target card).
Happy shooting,
Matthias
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Lots to learn and consider. There are wide ranges of interests, skills and abilities. If you are a bench rest shooter or a gun smith or just that PRECISE of an individual all of this is critically important to you.
I’m going to suggest if you’re happy with the way your gun shoots it’s all that matters and you don’t have to prove it to anyone but yourself.
The mean radius for this debate is probably closer to a couple five shot groups then anything else wouldn’t (most of us) agree
if you keep shootin you will eventually run out of ammo or screw up the group . Are ya happy then?
I’m going to suggest if you’re happy with the way your gun shoots it’s all that matters and you don’t have to prove it to anyone but yourself.
The mean radius for this debate is probably closer to a couple five shot groups then anything else wouldn’t (most of us) agree
if you keep shootin you will eventually run out of ammo or screw up the group . Are ya happy then?
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I’m wondering if shooting long strings introduces effects of eye strain and, if out doors, changes in lighting conditions. And what kind of optics do the different rifles have?
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Certainly for me perhaps others not so much. Optics? “The better I can see you with my dear”
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What LD said is what I try to do. Anytime I'm testing guns or ammo I will shoot Five ea Ten shot groups in a row, check group size and point of impact on paper for each 10 shot group. If groups are tight and point of impact is the same relative to point of aim for each group, 50 shots usually tells me whit I need to know.
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When I built the predecessors to the USFT Field Target rifle, I pondered long and hard to develop a method to "proof" accuracy for the Field Target game that I felt could win any legal Field Target event in the USA at the time (year 2000). I decided that a gun capable of sub-moa groups more often than not at over 50yards would do the deed if the gun held zero well enough.
I then constructed and underground tunnel 51 yards long, equipped with a heavy bench and protected "shooting hut" for testing. Thankfully, after a fair bit of tuning, and practice on the new bench, my first prototype proved capable of putting twelve consecutive five-shot groups on the NRA A36 (12 bull) target without great difficulty using a 24X Bushnel Elite Scope.
I measured all 12 groups ctc, then discarded the BEST and WORST ones from consideration. The average for the ten groups was under 1/2" (1 m.o.a is a little more than 1/2" at 50yds). The center of all groups was within 1/8" of the ten ring. I used that criteria for the seven hand-built FT rifles I made in my shop during the year and a half project. The first gun I shipped (to Steve Shultz) won about every important event there was, including the National Championships.
As it turned out, the zero didn't wander much on that design, so when Tim McMurray convinced me to help him make a production version, we found he was not able to spend the effort I did to shoot 12 good groups on the same card off the bench. I devised a new proof method for him, using a fixture that clamped the rifle to the bench to allow multiple shots to be fired into one group with only a short learning curve required. I suggested 31 shots in one group, though I recall that being reduced to 25 or so.
Tim's USFT version also won many, many events, including a number of National Championship matches, and the World Championship event held in Tennesee! There were lots of of equally accurate guns out there, but I suspect my design may be more trouble-free.
While it would appear that a gun clamped will always do better, I found this not to be true, and was generally able to best that method with the individual aimed shot method. I suspect this was due to harmonics issues.
So enough waxing the past .... I NOW rarely use that tunnel, feeling I need to proof my guns in the wind outdoors.
I then constructed and underground tunnel 51 yards long, equipped with a heavy bench and protected "shooting hut" for testing. Thankfully, after a fair bit of tuning, and practice on the new bench, my first prototype proved capable of putting twelve consecutive five-shot groups on the NRA A36 (12 bull) target without great difficulty using a 24X Bushnel Elite Scope.
I measured all 12 groups ctc, then discarded the BEST and WORST ones from consideration. The average for the ten groups was under 1/2" (1 m.o.a is a little more than 1/2" at 50yds). The center of all groups was within 1/8" of the ten ring. I used that criteria for the seven hand-built FT rifles I made in my shop during the year and a half project. The first gun I shipped (to Steve Shultz) won about every important event there was, including the National Championships.
As it turned out, the zero didn't wander much on that design, so when Tim McMurray convinced me to help him make a production version, we found he was not able to spend the effort I did to shoot 12 good groups on the same card off the bench. I devised a new proof method for him, using a fixture that clamped the rifle to the bench to allow multiple shots to be fired into one group with only a short learning curve required. I suggested 31 shots in one group, though I recall that being reduced to 25 or so.
Tim's USFT version also won many, many events, including a number of National Championship matches, and the World Championship event held in Tennesee! There were lots of of equally accurate guns out there, but I suspect my design may be more trouble-free.
While it would appear that a gun clamped will always do better, I found this not to be true, and was generally able to best that method with the individual aimed shot method. I suspect this was due to harmonics issues.
So enough waxing the past .... I NOW rarely use that tunnel, feeling I need to proof my guns in the wind outdoors.
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Good explanation LD. Hey, don't close down that tunnel, I use it all the time. Mostly used to test pellets, speeds, and also to set windage on my rifles, since its hard to find a good calm day to adjust scope windage...
Appreciate the explanation on the Simple Simon, your predecessor to the USFT. I'm sure a lot of guys on here don't know who you are, but they should. Since I've started shooting with you, 25M BR, 50 yard BR, the 100 yard steel plate, and the 115 yard Long Range Challenge, plus all the discussions we've had about airguns in general (and sometimes politics
), I've become a much better shooter. I've got my .177 FX Crown ready for FT, so that's the next step for me in the airgun learning process...Mike
https://www.airgunnation.com/topic/evolution-of-22-crown-stx-to-177-st/
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