What is the accepted group size to measure MOA
- Thread starter scianna54
- Start date
I read the update at the end where it says 5 or 6 shot groups.
More rounds there is, more statistically signifiant they become. To have confidence in you load - gun and shooters - 25 rounds without discounting flyers start to give you a good topo.
Doing 5 groups of 5 one day, same another day, give you a good pictures of your set up capabilities.
A hunting gun - you want to know the first cold bore shot and one or two more shots. Cold and warm weather.
A F Class gun - maybe more in the 100 rounds…
In Benchrest - 50 rounds consistent repeatable accuracy rounds is a must.
Before someone can say it is a one moa or a 1/4 moa gun..some work need to be done to prove it, at least to oneself.
Doing 5 groups of 5 one day, same another day, give you a good pictures of your set up capabilities.
A hunting gun - you want to know the first cold bore shot and one or two more shots. Cold and warm weather.
A F Class gun - maybe more in the 100 rounds…
In Benchrest - 50 rounds consistent repeatable accuracy rounds is a must.
Before someone can say it is a one moa or a 1/4 moa gun..some work need to be done to prove it, at least to oneself.
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- Location
- Western Manitoba
Is a good question - some people want to claim or "brag" how accurate their target or hunting rifle is - so they want to use "groups" - and sometimes discount holes that are not where they want them - calling those to be "fliers". Is other kinds of shooters who want to pull off a "cold bore" hit - so a single shot, for all the pesos. Is no "group" that matters, because a "group" of shots is not fired, at that time.
So some statistics kick in - I think - what you really want to know, with sufficient certainty - is where will your next shot go - the shot that you have not fired yet, based on where the last ones that you fired went. As per basic statistics - the more shots that you fire - the larger is your "sample" - the more certain you might be where that next one goes - a higher "confidence level". I do not have enough statistics training to know exactly how many is "enough" - some say 5 shots, some say 7 shots. I think I read that US Army will do or used to do 4 x 10 round groups to evaluate a batch of ammo for their purposes. I know of other bench rest guys that will fire 4 or 5 x 10 round groups to evaluate which lot of rimfire ammo that they will use in their next match - as I understand that - the issue is how certain do you want to be, where the next shot will go - if you just want to "brag" - then claim whatever you want.
Is some "magic" math stuff that I do recall from many years ago statistics classes - given a size for a 3 shot group, you can calculate what larger size is likely for the 5 shot group, and what is likely the even larger size for a 10 shot group. So, sort of tongue in cheek - the tightest "group" will be with a single shot - from there, the more times that you fire, the bigger that group will likely get.
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They don’t if you shoot more than one ..
By the way..some good reading here:
https://precisionrifleblog.com/2020/12/12/measuring-group-size-statistics-for-shooters/
https://ontargetshooting.com/measuring-rifle-accuracy/
By the way..some good reading here:
https://precisionrifleblog.com/2020/12/12/measuring-group-size-statistics-for-shooters/
https://ontargetshooting.com/measuring-rifle-accuracy/
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It depend on the use of the gun. A hunting gun , might have to shoot 2-3 fast rounds.
In F Class - maybe 10.. and more.
In Benchrest - 5 shots + sighters 6-7 shots in 7 minutes time.
In my view the gun should be shot in the manner and purpose it will be used. Then you will know what to expect out of your setup.
Testing loads..there is no need to shoot fast..it’a a good idea to wait..heat reduce barrel life..
Practicing for competition - shooting in the time allowed is the way to go in my book.
In F Class - maybe 10.. and more.
In Benchrest - 5 shots + sighters 6-7 shots in 7 minutes time.
In my view the gun should be shot in the manner and purpose it will be used. Then you will know what to expect out of your setup.
Testing loads..there is no need to shoot fast..it’a a good idea to wait..heat reduce barrel life..
Practicing for competition - shooting in the time allowed is the way to go in my book.
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- Location
- Western Manitoba
Maybe some get confounded between "accuracy" of a rifle, shooter and load, versus how well "sighted in" is that rifle, shooter and load. As mentioned above - depends what you are doing - sometimes really accurate, very tight groups are most important - even though hitting several inches away from the aiming point. At other times, hitting that aiming point, or a particular place in relation to that (3" high), is most important.
- Location
- Western Manitoba
Perhaps is a LOT to be found in the "details" - I think was an article by John Barsness - no longer certain - a particular custom gun maker guaranteed 1/2 MOA accuracy - and usually delivered that - even though with 30 caliber Round Nose bullets - not as if many hunters going to use that in their 308 Win - but that rifle would meet that "guarantee" with those loads.
There are 120 possible unique 3 shot groups in a single 10 shot group. If the purpose of shooting a single 3 shot group was to predict the size of the 10 there are 8 right answers and 112 wrong ones. If you shot 3 3 shot groups and picked the worst 1 you would have a 1 in 2.666 chance that your worst group would match the size of the 10 shot group. The other 2 mean exactly nothing.
Feeling lucky?
Feeling lucky?
There are 120 possible unique 3 shot groups in a single 10 shot group. If the purpose of shooting a single 3 shot group was to predict the size of the 10 there are 8 right answers and 112 wrong ones. If you shot 3 3 shot groups and picked the worst 1 you would have a 1 in 2.666 chance that your worst group would match the size of the 10 shot group. The other 2 mean exactly nothing.
Feeling lucky?
nCr = n! / (r! * (n - r)!) //n is the total number of shots, r is the number of shots to be chosen
10C3 = 10! / (3! * (10 - 3)!)
= 10! / (3! * 7!)
= (10 * 9 * 8 * 7!) / (3! * 7!)
= (10 * 9 * 8) / (3 * 2 * 1)
= 120
Gosh, never looked at it that way, I'll try to remember that, thanks! (252 possible 5 shot groups)
Do you mean what is the number of shots in a group? MOA is very close to 1 inch groups at 100 yards.
The number of shots used to determine moa doesn't really matter either... you would simply state it shoot moa with 3 shots, or 5 shots, or ten shots... what ever it does.
Personally with my hunting rifle I would shoot 3 shots one day, 3 shots another day...etc... until I had 5 groups... a good rifle would be shooting 1/2 inch or roughly 1/2 moa.
If you want shoot 3 shot groups; shoot at least 3 of them then stack the targets and measure across the whole stack. You can easily see through the paper. It is what it is at that point.
if Sub MOA doesn’t mean that that combination will put the rest of the supply and all future ammo of that type into a pattern of less than 1/60th of a degree then it doesn’t mean anything.
if Sub MOA doesn’t mean that that combination will put the rest of the supply and all future ammo of that type into a pattern of less than 1/60th of a degree then it doesn’t mean anything.
I just thought there was a standard as to how many shots you have to make in a row in order to make a claim like "my rifle shoots MOA". 5 rounds would make sense to me because many rifles hold that many rounds.
You like your numbers?
One shot. Now, if you want to confirm that 95% of your shots fit within 1 MOA, that's a different answer. 99% of your shots fitting within 1 MOA, a different answer again.
