Ten Shot Groups?

[Picher]

There's an article in this month's Shooting Times magazine, touting the advantages of 10 shot groups. I shoot three or five shot groups and can glean all the information necessary, providing they're reasonably tight groups. Our club range is usually quite windy, so we tend to take a while to get about the same conditions for five shots. I'd be there about all day to shoot a ten shot group.

What do you folks think about 10 shot groups?

 

[denton]

The statistics of group size are.... ummm... a little hard to handle.

You can make sense out of any size group you choose, provided you shoot enough of them.

People often make the mistake of saying that they never shoot more than 3 shots at an animal, so a 3 shot group is all that matters. That's a fallacy. The useful question is, how well does a 3 shot group predict the size of the next 3 shot group? The answer is not very well.

If you have a rifle that will average 1" five-shot groups over many, many groups, it will routinely print 5 shot groups as small as .5" and as large as 1.5" with absolutely no change in the rifle, shooting technique, ammunition, etc. So even a 5 shot group isn't very statistically strong.

A good balance between precision and cost is the average of 3 five-shot groups. That will estimate your long term average group size within about +/-25%.

If someone wants to shoot 10 shot groups, then the right procedure is to take the standard deviation of the shots measured from the center of the group. And nobody is going to do that in the field.

 

[someguy2800]

I usually shoot 5 shot groups until I have narrowed in on a reasonable load just for the fact that ammo costs money. I don't think a 3 shot group is enough to really make an informed conclusion. Just as an example here are two ten shot groups I recently shot in my 7.62x39 AR15. These are both junk steel case commie ammo so neither is particularly accurate.





Same ammo shot on another day





I've shot several boxes of both of these and the results are consistant. The "hotshot" ammo always has 6 or 7 out of 10 grouping fairly tightly but the rest are all over the place and it gets much worse with distance so I think it might be a stability problem. When shooting steels at 200 yards at least 3 out of every magazine will miss the target completely. The wolf ammo does not group quite as tightly but there are much less wild flyers and at 200 yards all 10 rounds will hit there mark.

If you were to only shoot 3 or 5 shots of the hot shot ammo you may see only the tight center grouping and not see the wild flyers, and conclude its the better ammo, however when shooting a larger group size at a longer range it becomes apparent that the wolf ammo actually gives a higher hit percentage.

However when you have a good rifle that can really group such as this 5 shot group from my Tikka 25-06 with handloads at 100 yards, well your just wasting bullets and powder shooting more than 5 shots

 

[anymanusa]

I'm not good enough to hold to that standard. If I can get three, that tells me nearly everything I need to know about the accuracy of my firearm.

 

[.308 Norma]

There's an article in this month's Shooting Times magazine, touting the advantages of 10 shot groups. I shoot three or five shot groups and can glean all the information necessary, providing they're reasonably tight groups. Our club range is usually quite windy, so we tend to take a while to get about the same conditions for five shots. I'd be there about all day to shoot a ten shot group.

What do you folks think about 10 shot groups?

I'll read the article before outright claiming for certain that the author is full of it, but my initial, knee-jerk reaction is; "What a waste of time, bullets, powder, primers and wear on cases."
By the way, speaking about wind, in this part of Idaho, we have a saying about the weather. It's, "If you don't like the weather, wait 10 minutes and it will change." However, the gusty wind is a constant. We don't have a real shooting "range" around here, but because of our constant, gusty wind I know what you mean about how long it would take to shoot 10-shot groups that provide any more information than our 3 or 4 shot groups. We'd be spending all day at the county gravel pit. Which is okay since we're both retired. But talk about boring!

 

[NWPilgrim]

From a statistical perspective 3-5 shots are not enough to establish any significance. Software such as OnTarget allows you to superimpose multiple smaller groups into one large group that is statistically significant.

But I think in practical terms it comes down to what you are shooting for. If you want to definitively establish one ammo/rifle combination as more accurate than another then you need to have statistically relevant amount of data, such as 30 shots. But if you are just looking for a good hunting load then as long as it hits within an acceptable target area every time you shoot whether it is one shot or ten that is all that matters.

I think most of us try to find the number of shots that gives us some relative confidence, even if absolute group size is much larger. For instance, I find that 10-shot groups are about 50% larger than 5 shot groups. 30 shot groups even a bit larger. Beyond that the size of the group should not increase much. So your specific 3-shot group may be 1". But that is just a small sample of the entire area that any one shot could land. If the 30-shot group is 2", than any of those three shots could have landed anywhere within that 2" area, so your 3-shot groups over time may vary from 1/4" - 2" for the exact same ammo/rifle combination.

So, if you are comparing different loads with 3-shots and one is 1/2" and another is 3/4" then there is not enough data points to determine if the first load will always shoot smaller groups than the second. It could be just coincidence for that instance that #1 was smaller than #2. If they were each shot for 30 rounds, then you may find that in the long run #1 actually produces 2" groups and #2 gives 1.5" groups.

I believe the NRA uses five 5-shot groups for their accuracy comparison, or 25 shots.

I know what a pain it is to use even 10-shot groups when you are working up a test ladder and then comparing different powders, bullets, seating depths, brass, primers, etc. And those 3-shot groups can be so enticingly small. We all want that sub-MOA or 3/8" group and it is easier to get that, even if only occasionally, with only 3 shots. Not so much fun to talk about a 1.5MOA - 2.5MOA rifle, but truer.

And then to be even more precise in our comparison we should be comparing mean average distance from center of the group rather than the extreme spread. Extreme spread tells us the absolute furthest any shot will land from another one for that load. But it does not give us any idea how likely it is they are to be mostly grouped with one or two outliers, or are they evenly dispersed in that area? I'm sure we have all had groups where one load was mostly tightly bunched into 1/2" with a couple out to 1 1/4", and another load where shots were more evenly dispersed in an 1" diameter. Intuitively we are attracted to that 1 1/4" load because so many shotes were actually much smaller. And using the mean average would tell us that it would be very likely for any one shot to hit 3/8" from POA, whereas the evenly dispersed group might show 1/2" from POA.

If we are just comparing our own loads then we can establish whatever standard suits our purposes. But to compare one of our loads and rifles to someone else's, or to truly establish which load is statistically more accurate then we need to be shooting multiple small shot strings superimposed, or one large string of about 30 shots. I think for ease and comfort of shooting that is why NRA breaks into five, 5-shot groups.

Personally what I do is shoot 10-shot groups to whittle down the many loads I am comparing to the 2-3 best ones. And then I compare multiple 10-shot groups to determine which of the top three is really the best. When working up .30-06 or similar loads I only shoot 5-shot groups. If you ever get a sum-MOA 30-shot group then you really have something for a production rifle. But using mean average also reduces the size from extreme diameter to average radius, so then it is easier to get sub 1" mean average groups of even 30-shots.

Whew. I need to go shoot some more!

 

[MCMXI]

The useful question is, how well does a 3 shot group predict the size of the next 3 shot group? The answer is not very well.

I agree with this statement and will add that the real problem with groups is that people don't track where the group center is for each group. Someone can argue that they shot three 3-shot groups that were all under 1 moa at 100 yards so they know that their rifle/ammo combination is sub moa "all day long". What they don't do is overlay those 9 shots to show the results of a single 9-shot group. Many people are much better at shooting groups (precision) than they are at hitting what they're aiming at (accuracy). You can learn so much more by shooting 10-shot groups. You'll see trends that you simply won't see with 3-shot or even 5-shot groups.

For example, I shot two 10-shot groups while testing some new 6.5 CM hunting ammunition (140gr SGK) that is handloaded by an ammunition manufacturer. I shot two groups on different days and didn't "call" a single shot i.e. every shot felt good. With the first group the outlier was shot #9 whereas for the second group the outlier was earlier in the shot string, #3 or #4 I think. Notice that both outliers are in a similar position relative to 90% of the group. Based on only two 10-shot groups I believe that both outliers are due to the load e.g. neck tension, bullet concentricity, charge etc., but what if I shot two more 10-shot groups. Maybe the outliers would be on the other side of the 90% group which would change my thoughts on how reliable this load is. The outliers might not have shown up as dramatically or at all with 3-shot groups. Given the outliers below, I'm confident that the load is a .75 moa performer, but without that information I'd be convincing others that the load is half that "all day long". In truth, I'd need to shoot at least three more 10-shot groups to increase my confidence that the load is a sub .75 moa performer.

For me, I want to know the greatest distance that a shot will land away from my point of aim. Claiming that a rifle/optic/load combination is a sub moa system based off a bunch of 3-shot groups without any information regarding the location of the group center relative to the point of aim is ridiculous.

 

[milemaker13]

I think have a misunderstanding of shooting groups! I shoot ten shot 'groups' all the time.... Over and over. Shooting is fun!

I really need to move some place better where I can work on my hand loads, shoot those time consuming groups you guys are talking about and generally get more (and higher quality) time with my guns. Oh suburbia! Thou art a cold and heartless (edited)!

 

[cougar1717]

Just like anything else.... it depends.

IMHO, 3 shot groups are like rose colored glasses. If you shoot enough of them, you will see what you want to see - ie an accurate rifle/load. If one shot opens up the group, it is called a "flyer" and more 3 shot groups are shot until you get a picture worthy of bragging about on the internet.

Multiple five shot groups give you the ability to get an aggregate average over time. Obviously if you're using a chronograph to figure out SD and ES, that magic number for a statistically valid results is around 30. It doesn't take too many trips to the range to get six reasonable groups of five to be able to have some reliable data. You can see your data come to life, like a group that opened up to X moa because of the 15mph wind, and so forth.

I do like ten shot groups because very little can be hidden. Almost nobody likes to post their 10 shot group totals probably because most people don't have a rifle / ammo / skill combo that can shoot ten sub-moa (and who is going to admit to the internet that they aren't a sub-moa shooter, right?). I'm not saying that I have this ability, but who likes posting 10 shot 2-2.5moa groups? The larger issue with 10 shot groups is the shooter's ability to make consistent shots. Concentration and your routine become more important and the question becomes - was it the rifle and ammo or the shooter?

So, for heavy recoiling firearms, I still like 5 shot groups. You can aggregate them and it gives a shooter time to rest and barrels time to cool.
Light recoiling firearms, especially for load workups, benefit from 10 shot groups to see a worst case scenario. Multiple 5's can get you reliable data.
For rimfire and other super-light recoiling firearms, 10 shot groups really tell you how good your ammo is and many fliers are in each box.

 

[ColtPythonElite]

I don't care how many shots a guy wants to call a group as long as he doesn't disregard that one way out in left field and proclaim it a fly when he is doing his measuring for bragging rights...lol

 

[murf]

thirty shots minimum (however you want to do it) to catch all your "flyers". a good way to do this is to; set up your target. fire three, five, ten, or whatever, shots. put a paster on your target (make sure to line up the bullseye). fire three, five, etc. more shots. repeat until you have fired thirty shots.

the pasters will give you your three, five, etc. shot groupings. the original target will show your overall thirty shot group.

shoot the group(s) like you will shoot in the field, at a match, etc. if deer hunting, shoot three shot groups, wait a while for the barrel to cool down then shoot three more and repeat to thirty shots fired. a ten shot string match? shoot ten shot groups. varmint hunting? shoot five, or ten shot groups (depends on the varmint). etc.

my opinion,

murf

 

[Nature Boy]

I’ve more or less settled in on this process to find the most accurate loads and use different group sizes for different purposes. Basically:

1. 3 shot groups at 100 yards to find the best powder load (accuracy node). Minimum of 6 groups. Comparing the center of adjacent groups looking for the least amount of vertical deviation. For example:



In this case there’s a very wide node between 42.0g and 43.0g. I’ll also run a similar test for optimum seating depth.

2. If necessary I’ll shoot a couple of 5 shot groups just to validate what the tests above showed me.



3. I’ll take this load out to 500 yards and shoot some 20 shot groups. This is really a test of the entire system. Me, the rifle and the load.



The value in doing any of this really comes down to the individuals ability to be consistent in reloading and shooting techniques. That way the data speaks. Isolating the variables, namely me, is what allows the data to come through and tell me what I’m looking for

 

[denton]

OK... just one objection so far:

When you're dealing with Z scores (Normal Distribution) you need about 30 observations minimum. That's because tests with the Normal Distribution assume that you have the population mean.

But nobody uses Z scores. Everybody uses the T Test, and that only assumes that you have an estimate of the population mean based on a sample.

For some reason, the 30 observation requirement sticks in most people's mind. In reality, there is no such requirement for the test almost everyone uses.

Characterizing variation is a lot harder than characterizing the mean. You can often do a meaningful T Test with two samples of 4-5 items. Testing variation takes a lot bigger samples.

 

[Offfhand]

It has been interesting looking at the targets posted so far on this thread. Looking at groups, and shapes of the groups, one has to wonder how much is due to target induced error.

 

[Nature Boy]

It has been interesting looking at the targets posted so far on this thread. Looking at groups, and shapes of the groups, one has to wonder how much is due to target induced error.

I’d love to hear more on this

 

[Walkalong]

What do you folks think about 10 shot groups?

They are great, but tough on the shooter and equipment.

I tend to start with three shot groups to see if I need to waste any more ammo with a load, then 5 shot groups.

 

[Picher]

Clearly, some of you are really dedicated target shooters. I just want to get my hunting/varmint rifles to shoot under a half-minute. A quarter-minute is even nicer, but not worth the futzing with most hunting rifles.

However, years ago, a guy on one of the gun boards was determined to break the braggers from the "shooters" and instituted the Prove-It target, which could be downloaded to 8 1/2" x 11", containing 10 bulls and one sighter, to be shot at 50 yards. I took the test with my 10-22 and managed to average .37" for all ten groups.

One group was just under 0.1", as I remember. It was the most bored I've ever been when target shooting and my neck was sore from holding it in shooting position. I did a couple more targets with other rifles, but decided that was a bit too much. My 10-22 target was in first place for a few weeks. I would never again shoot that many groups on one day and though I've shot ten shot groups with some .22s, would never consider shooting one with my centerfires.

 

[LoonWulf]

Ill shoot 10 shot groups with my .22 from time to time, mostly just because thats how many rounds my magazine holds. I shoot 3 and 5 shot groups with my centerfires, because thats what my magazine holds. I shot a 20rnd group with my AR this morning, cause well...thats how many rounds my magazine held. Yeah, its a trend.
It takes me about 2-5 mins to shoot a group, then usually a few mins to switch guns and do it again...i can do that for an hour then im pretty bored and plinking at stuff on the berm or rocks or cans or what ever.

I dont think i could manage to shoot a 10 shot group out of any of my larger rifles, without getting my barrel too hot to touch. Even my Ar was steaming (it was raining) after 20 rounds at what i consider a fairly average pace.

 

[CLP]

I shoot 3 shot groups and remove the two fliers. It's a strategy that's been a tremendous help in honing my skills.

 

[.308 Norma]

I shoot 3 shot groups and remove the two fliers. It's a strategy that's been a tremendous help in honing my skills.

Ha! Ha! Ha! Ha!
Good one CLP!

 

[Captcurt]

It is fun as well as satisfying to chew out one hole with 5 or 10 shots, but when we are talking a hunting gun I want to know where that first shot out of a cold barrel is going. It has been a long time since I have had to pull the trigger twice on a deer.

On the other hand, one of the best 22 rimfires that I have owned would shoot a 10 shot group about the size of you pinky nail at 50 yards. I still managed to miss squirrels with it on a regular basis.

 

[Everready73]

I usually do a 5x5 Target. 5 shots 5 groups and take the average for accuracy potential of a firearm. I think 10 round groups are great but believe they add more human error than a 5 shot group

 

[Ru4real]

I shoot 10 shot groups with pistols and rifles off a rest and off hand when I'm testing.

Off a rest is meant for selecting the most accurate load; I'm testing the gun/load combination. Off hand is for meant for strength training / breathing exercise; I'm testing me.

 

[NWPilgrim]

Here is a great article about both precision and practicality from a PRS competitor:

http://bulletin.accurateshooter.com...half-moa-how-much-precision-is-really-enough/

Excerpt:

"What is your standard of accuracy? How good is “good enough”. Jim See, a skilled gunsmith and successful PRS competitor, has answered that question for his tactical discipline. For the kind of matches Jim shoots, he likes to have a rifle that will hold half-MOA for five (5) shots, 3/4-MOA for 15 shots, and 1 MOA for twenty shots."

 

[jmr40]

Three shot groups tell you about the accuracy of the ammo. Five shot groups tell you about the accuracy of the rifle. Ten shot groups tell you about the accuracy of the shooter. It depends on what your goals are.

I've shot enough to know what I can do and what my rifles will do with good loads. If I'm shooting for groups at the range it is usually because I'm wanting to see how a hand load shoots so 3 is the norm for me with centerfire rifles. With 22's, handguns, and sometimes with 223 I'll shoot 5-10 shot groups since ammo is cheaper.

I'm a hunter, not a target shooter so 1 MOA is my goal. I quite often get 3 shot groups of 1/2 MOA and sometimes much better. Most of my rifles hover around 3/4 MOA. But I don't obsess with anything smaller than 1 MOA. When shooting from field positions while hunting you can't take advantage of anything better. It ain't the same as shooting off a bench.

Here is a good link that talks about how little of an advantage a 1/2 MOA rifle is compared to a 1 MOA rifle. And these guys are shooting from a rest at 700 yards. At closer ranges and in the field the advantages are even less. This is a calculation of the probability of hitting a 10" target at 700 yards with different degrees of accuracy. There is a good graphic that says it all if you scroll down just a little.

http://precisionrifleblog.com/2015/04/15/how-much-does-group-size-matter/