# of Shots per Group and MOA - Results

[JASmith]

This is an excellent discussion!

There is a very nice statistical approach to estimating actual accuracy based on group size and number of shots. See the Long Family Discussion

For hunting purposes, another approach can be found here: The Hunting Zero. This essentially allows one to average the first shot over several shooting sessions (difierent days, weeks, lighting, etc.) to infer true accuracy and zero. The technique also tracks the same hit information for the second an third shots to capture the difference between a cold, possibly clean, bore and a fouled warm bore.

 

[speedengineer]

This is an excellent discussion!

There is a very nice statistical approach to estimating actual accuracy based on group size and number of shots. See the Long Family Discussion

For hunting purposes, another approach can be found here: The Hunting Zero. This essentially allows one to average the first shot over several shooting sessions (difierent days, weeks, lighting, etc.) to infer true accuracy and zero. The technique also tracks the same hit information for the second an third shots to capture the difference between a cold, possibly clean, bore and a fouled warm bore.

Very interesting! It looks like the author of your first link, Chris Long, performed a very similar analysis as I did and arrived at very similar results! It looks like he chose to define a standard 1MOA rifle as a rifle who's shots impact within 1" circle 68% of the time (one standard deviation). Good stuff.

The Hunting Zero looks like a smart way to track and determine your zero to be accurate for those cold bore shots. I definitely plan to continue tracking my first shot hit locations for each range trip I take.

Thanks for sharing

 

[LRNut]

The Hunting Zero and a link on MPBR were good; I get really tired of writers and shooters who cite the old Jack O'Connor method of 3" high at 100 is best. Such a zero normally means you are going to be 4" high from 140-180 or thereabouts, which means you have to shoot 2 inch groups in the field at those ranges or risk missing high (half the bullets are going to be higher than 4" - the exact distance they are high is a function of your ability to shoot and the inherent accuracy of your rifle). Two inch groups at 180 yards is not a problem if prone or even sitting with a bipod or sling, but generally game at that range is aware of you and/or will be if you dick around with a bipod, shooting sticks, etc. In other words, perhaps you shoot sitting with no support, or even offhand if you are that good. Most shooters cannot shoot a 2 inch group standing or even unsupported sitting at 180 yards.

 

[ilc]

Oh, and also....Will someone please tell me what MOA my rifle shoots?

.25 all day, (as long as you do your part!)

Seriously though, this has to be one of the best posts I have ever read on this forum. Unfortunately, despite its clarity and simplicity, we still get people coming up with lame excuses as to why they choose to define their rifle's accuracy using low-shot-count groups.

Mr SpeedEngineer Sir, a challenge, should you choose to accept it! Would you turn your brilliant analytical mind to the practice of one-shot-per-charge-weight ladder tests? I fear another sacred cow might be facing the captive bolt gun....

 

[rickhirsch]

while back I had a 270 wsm I tried all kinds of different loads. the thing would shoot half way
decent was 110 gr. barnes . but I noticed that usually the first two shoots were snake eyes .
I had months before the deer season. I thought would shoot a shot or two a week. and
see if the gun would still stay close for couple weeks I ended shooting that gun for 9 weeks
and after 9 weeks it was a little over and inch for twelve shots . had I shot three shot or five shot
groups. I couldn't have taken that gun hunting. all that being said I did change the barrel.
but I learned some things you don't have burn a barrel to that the gun shots great. 27 shots
three shot groups will give your bell shape curve . it also cracks me up. how many 1/4 moa guns .are out there! I just did my first 600 yds. bench rest shoot last mouth. my gun shooting about 2.250 @ 600 yds. practice.
not bad right . I finished my agg at the shoot with a 4.625. so wind sucks. and there were no
1/4 moa guns at the shoot . I mean none! I liked the article it was simple and to the point.
thanks buddy . we need more articles like this. simple is best. thanks buddy old rick.

 

[Mikecr]

I get so tired of hearing folks say "Three shot groups are good enough because I never shoot more than three at an animal."
This just demonstrates a complete lack of understanding of statistics and probability.

Long range hunting does not include grouping, nor shooting aggregates.

 

[JASmith]

Long range hunting does not include grouping, nor shooting aggregates.

Can you expand on this comment?

It can all too easily suggest that one does not need to understand the accuracy and precision of the rifle to have confidence of anchoring an animal at long range.

Groups are absolutely necessary to do this. Repeating the group (even just a single shot per "group" if one desires) over multiple sessions spread over days and weeks develops more confidence that the rifle will place the bullet in the intended area.

 

[LRNut]

Can you expand on this comment?

It can all too easily suggest that one does not need to understand the accuracy and precision of the rifle to have confidence of anchoring an animal at long range.

Groups are absolutely necessary to do this. Repeating the group (even just a single shot per "group" if one desires) over multiple sessions spread over days and weeks develops more confidence that the rifle will place the bullet in the intended area.

I am dying to hear an explanation as well.

 

[skipglo]

Are you an accountant???

Ballistics Engineering is my best guess x .0123456 calculas ÷ WAY TOO MUCH THOUGHT AND TIME! If you are looking for PHI as your answer although you may have to use 7234 possible permutations and calculations....you can always get PHI

 

[tripdad]

By the 3 shot standered that most use as my gun shoots x moa or should i say o.x moa lol. All my rifles shoot sub 0.25 moa, by that i mean all have shoot a sub 0.25 moa 3 shoot group at some point. But of course all have 3 shot groups over 1 moa. For my purposes for the accuracy of a rifle ill shoot 3-4, 5 shoot groups and the average of that is what i call the rifles accuracy and all my rifles will shoot at or under 1 moa, if they don't i keep working on them till they do or they find a new home. This is for hunting guns

 

[Mikecr]

My perspectives:
Accuracy is the most powerful of all ballistic attributes.
Accuracy prints as proximity to your mark.
Accuracy is demonstrated by any & every single shot.
Accuracy per distance per condition(system/field) defines your hunting shot capability.
Number of shots beyond one cannot be relied on for hunting.

Accuracy IS NOT defined by a minimum number of shots per distance, nor proximity between shots.
This quality is called Precision, and has zero utility with hunting.
The averaging of either few or many shot printings means nothing to hunting shot capability.
Bottom line; this is 5 missed groundhogs in a row (unless he was aiming for that dime):

Now you could suggest the simple 'dial the scope a few clicks this way and a couple that way' to hit your mark.
That'll work while the barrel is still hot, and don't dare moving the gun doing it.
Then, go ahead and let the barrel cool, and put a single shot into an moa relative X @ 100yds today.
Tomorrow, put a single cold bore shot into an X @ 200yds.
Go 100yds or 50yds or 25yds further each day and do this.
Run the numbers on what you're actually doing there, instead of imagining how things might be (statistically) .

 

[LRNut]

My perspectives:
Accuracy is the most powerful of all ballistic attributes.
Accuracy prints as proximity to your mark.
Accuracy is demonstrated by any & every single shot.
Accuracy per distance per condition(system/field) defines your hunting shot capability.
Number of shots beyond one cannot be relied on for hunting.

Accuracy IS NOT defined by a minimum number of shots per distance, nor proximity between shots.
This quality is called Precision, and has zero utility with hunting.
The averaging of either few or many shot printings means nothing to hunting shot capability.
Bottom line; this is 5 missed groundhogs in a row (unless he was aiming for that dime):
View attachment 203515

Bench rest shooters don't care about where the group lands; all they care about is size.

Obviously, if you are hunting, you want to place the first bullet into the vitals. I often drive 45 minutes just to take one shot at long range; simulates hunting. I rarely shoot more than one bullet because I now know the wind. To your point, if my goal was to hit a 12 inch circle at 800 yards 90% of the time, I could miss with shot number 1, correct for the wind, then hit 9 more times and convince myself the probability of connecting at 800 is 90%. A better exercise is to go out and shoot one bullet every hour, or even better, one bullet a day over ten days.

However, to say aggregates don't matter is really saying you are ignorant of probability and statistics. What we are trying to do is ascertain the odds of missing when all else is perfect. If my rifle shoots 8 inch groups at 800 yards, I have only 2 inches of allowable wind drift before I risk missing (granted, not a great chance of missing, but a chance). A rifle that shoots 1/2 MOA has TWICE the allowable wind drift error that a one MOA rifle has.

Perhaps I am just not comprehending what you are saying...

 

[Lee Goodwin]

If this were 800 yards out would this be close to 1 MOA ?

 

[tripdad]

Mikecr, so i guess it takes you 3 or 4 months to work up a load and test it to find out how it shoots if it only maters what it does on cold bore shot then another month to do seating depth test. I don't have that kind of time or money. So i find out what gun will do then check to make sure where it hits cold bore, i do shoot more than 1 time a year to see if scope is on so every shooting session starts out with cold bore shoot and if my gun doesn't hit where i intend it i look for why its not. the OP was asking how we judge accuracy, and did 1 heck of a job with his graphs and figures, i found it very interesting