Out of curiosity and for arguments sake. Why say 5 or 7 is enough? Why not 10 shot groups or 30 shot groups? There is going to be some human error with anyone's shooting and environmental differences on different days or even hours. So at what point do you decide your rifle is capable of "X" size groups and why do you pick that arbitrary number of shots?
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Are three shot groups valuable?
- Thread starter LRNut
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When I shot a lot of service rifle, I test how the shooting system handles a full string. Our EIC 600 yards matches are shot in 20 minutes ... NO SIGHTERS.
Here is my favorite target to test at short range reduced SR3 (300 yards) at 200 yards; prone, sling, irons. X Ring is 30 caliber smaller than a minute.
When I shot a lot of service rifle, I test how the shooting system handles a full string. Our EIC 600 yards matches are shot in 20 minutes ... NO SIGHTERS.
Here is my favorite target to test at short range reduced SR3 (300 yards) at 200 yards; prone, sling, irons. X Ring is 30 caliber smaller than a minute.
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I was assuming since it was a 300 RUM he was talking groups for a hunting rifle but I may not have read/interpreted his post correctly. I could see this for this type of competition. Nice shooting.
Mike Matteson
Well-Known Member
I haven't had much problem even with a clean barrel. I prefer a fowling shot. After the fowling shot and even on another day I shoot the rifle, and haven't clean it. I haven't had much problem it the bullet going where is pointed at. I do know that some rifle want to be clean and other dirty. I will still use a fowling shot to start with.
Statistically it takes 8-9 shots to produce a representative sample. Shooting fewer than shots doesn't guarantee you have a representative sample. Shooting more isn't likely to change results unless you also want to test something like how a barrel will preform as it heats up. Here's a pretty good video that explains it:
There's also a video from Bloke on the Range that goes deeper into the statistic side of things.
Good video and from someone who knows alot more about this than me. With that being said I still question his logic on one thing. The difference in groups overall was roughly .24" which is a hair under 1/4" between 3 shot and nine shot groups with the five shot groups in the middle at roughly 1/8". He called fliers on the 3 shot but not the 5 and 9 which is how I came up with the roughly 1/4" difference if he didn't call the fliers. Since a human is human and not perfect IMO a 1/4" difference at 100 yds is well within the tolerance of human error especially with 9 shots and not necessarily a load or rifle problem. It is also my opinion if I shoot a .375 three shot group including the cold bore shot and go and do the same with multiple trips to the range with the same point of impact. I have a fine load and rifle. Shooting at further ranges may affect my opinion.
Yeah, I don't really know what was up with the flyer thing. They should have done it for all or none. I don't like the idea of discarding some shots as fliers or taking 80% groups in most situations. Usually that "flyer" is just a part of the group and over many rounds wouldn't look like much of a flyer.
Some of it could be human error, but there's also the issue of 3 shots not being a representative sample, which is what they're trying to demonstrate. They didn't really go into the statistics in that video, but this video touches on the statistics without getting deep into the math:
If you want something that's a pretty lomg and dry read but goes into everything from group size to why discarding flyers probably isn't a good call this article from PRB and the other articles they link to cover it all pretty well:
Precision & Group Size – Statistics for Shooters Part 3
This article is going to dive into the most effective ways to quantify the precision of a rifle and...
The other glaring issue in the first video is the use of ammo that is, by their own admission, sloppy. That likely had a negative affect on the consistency from one group to the next. I also wish they would have created an aggregate group from each group size for comparison, which should have made it clearer that small groups don't provide a representative sample. In all likelihood there would be little to no difference in the size of the aggregate groups.
If you can ensure your groups are shooting to the same point of impact or overlay your groups into one big group multiple 3 shot groups work well. I typically use Photoshop to overlay 3 or 4 3 shots groups when I want to do that, or I'll shoot benchrest card and overlay all the individual shots. Ultimately that's the same as shooting a single larger group, but it's easier to test a load over multiple days and ensures you don't shoot out the point of aim.
Try this for a test. 28 5 shot groups from 2 barrels. 1.00 inch at 200 yards
Yeah, I don't really know what was up with the flyer thing. They should have done it for all or none. I don't like the idea of discarding some shots as fliers or taking 80% groups in most situations. Usually that "flyer" is just a part of the group and over many rounds wouldn't look like much of a flyer.
Some of it could be human error, but there's also the issue of 3 shots not being a representative sample, which is what they're trying to demonstrate. They didn't really go into the statistics in that video, but this video touches on the statistics without getting deep into the math:
If you want something that's a pretty lomg and dry read but goes into everything from group size to why discarding flyers probably isn't a good call this article from PRB and the other articles they link to cover it all pretty well:
Precision & Group Size – Statistics for Shooters Part 3
This article is going to dive into the most effective ways to quantify the precision of a rifle and...precisionrifleblog.com
The other glaring issue in the first video is the use of ammo that is, by their own admission, sloppy. That likely had a negative affect on the consistency from one group to the next. I also wish they would have created an aggregate group from each group size for comparison, which should have made it clearer that small groups don't provide a representative sample. In all likelihood there would be little to no difference in the size of the aggregate groups.
If you can ensure your groups are shooting to the same point of impact or overlay your groups into one big group multiple 3 shot groups work well. I typically use Photoshop to overlay 3 or 4 3 shots groups when I want to do that, or I'll shoot benchrest card and overlay all the individual shots. Ultimately that's the same as shooting a single larger group, but it's easier to test a load over multiple days and ensures you don't shoot out the point of aim.
I agree with everything you said. I look at the original post and I assumed that this was a big game hunting rifle. Right or wrong I want a rifle to shoot 3 shots staring with a clean cold bore to shoot under .5" @ 100yds to start before stretching out the distance.in my head statistically the more shots you fire the more chance for human error or conditions to change. Including wind, bore heat, etc. If I bring my rifle to the range and it and I accomplish this without a change in point of impact that is what I am looking for. I am not a competion shooter or shoot prairie dogs or something similar so shooting groups with more shots doesn't seem to me like it is giving me much useful information. The fact is if I need more than one shot to put down an animal I didn't do my job. It has happened to me more than once but it doesn't change that fact. If I need more than 3 shots to put down an animal I should not be doing what I am doing and go home to practice or maybe take up another hobby. I also don't foul my bore which may be right or wrong to some people but I want the same starting point every time.
Mikecr
Well-Known Member
Just be sure to produce your 'representative sample' -from cold bore shots (each).
And if one or two shots fall out of your killzone pile, don't delude yourself with a statistical notion that you're 90% capable. Instead, go ahead and consider it outside of your hunting capable range.
Mikecr
Well-Known Member
Sorry. Depending on each shot's POI (w/resp to center of mark) for X-size-group, or Y-size-group, the accuracy could be better or worse. The grouping can be bigger or smaller without a change to it's center, and with no shots getting closer to center of mark.
Your mistake shooting several shot groups is telling the rifle when the group starts. After a few shots, the rifle gets nervous about the group size. Rifles are like deer they can't count. Tell the rifle you're starting a new group on every shot....or tell the rifle you're just shooting for fun....not groups. Same concept might work for the shooter also.
Calvin45
Well-Known Member
I believe you. Rifles get nervous haha.
It's kind of like my English teacher back in high school. She told us that printers have a built in anxiety detector and when they detect that you're printing off your assignment at the last possible minute it can tell and then it doesn't work. She also told us that she didn't care, therefore, if we claimed technical difficulties as an excuse for being late…it only proved we had procrastinated too much and were getting what we deserved!!!!
Frank in the Laurels
Well-Known Member
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- Jul 15, 2007
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....cold bore one shot group is the only thing that matters in a hunting rifle, it will teach you the clue of NOT CLEANING your rifle after you get done with your final pre-season sighting session..
