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...
A good read... I am a believer in mean radius as my preferred metric....
First cast loads in the 308
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A good read... I am a believer in mean radius as my preferred metric....
Josh
Well-Known Member
Excellent article, explains more about what I was getting at.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
A good read... I am a believer in mean radius as my preferred metric....
RBHarter
West Central AR
A 1" 10 shot rifle is much more consistent than a 1 MOA 10 shot rifle ......
5 touching is pretty good even if they are a figure 8 chain in a 22 cal not so much out of a 12ga it's not even really good with a 45 cal .
We always presume 100 yd but lots of places and shooter's are 100 metres , another 10 yd . A metre being 39&a little inches and all .
Then there's the OD guys and the ID guys and the ID/OD minus 1 bullet dia guys ....the CTC guys .
Then there's the guys that are cranky because their $1200 86' won't shoot with the $400 110 ........
You know I had a rifle that I fought to a finish discovering in the end that it was just really touchy about case capacity.
5 touching is pretty good even if they are a figure 8 chain in a 22 cal not so much out of a 12ga it's not even really good with a 45 cal .
We always presume 100 yd but lots of places and shooter's are 100 metres , another 10 yd . A metre being 39&a little inches and all .
Then there's the OD guys and the ID guys and the ID/OD minus 1 bullet dia guys ....the CTC guys .
Then there's the guys that are cranky because their $1200 86' won't shoot with the $400 110 ........
You know I had a rifle that I fought to a finish discovering in the end that it was just really touchy about case capacity.
Petrol & Powder
Well-Known Member
Back in post #35 you wrote, “…..If I were to shoot 5 shots instead of 10, some of these groups would have been 3/4".…..”. So clearly you were getting ¾” groups from some 5 shot strings and then those groups opened up as you continued to add bullet holes to the group.
I'm not suggesting that you cherry pick 3 or 5 bullet holes out of a larger number of bullet holes to get the group size you want. As you point out, that would just be a confidence builder and not a true evaluation of the rifle’s capability.
Any measurement of a rifle's accuracy derived from a sample (like say 5 shots) is just that, a sample. A bigger sample size may be statistically more precise than a smaller sample size, but we’re pretty much stuck with extrapolating some measurement of a rifle’s accuracy by looking at fairly small samples of that rifle’s accuracy.
Most people use 3 or 5 shot groups to get some idea of a rifle’s potential accuracy. Yes, a bigger sample size (like say 10 shots) would be statistically a better yardstick. It would also take more time to avoid heating the barrel and it would consume more ammunition.
A larger sample size would be better in terms of evaluating the rifle, but a smaller sample size is likely good enough. A 100-shot group would be statistically a better sample than a 10-shot group but it wouldn’t be very practical. A 5-shot group probably isn’t the best yardstick, but it is a fairly common yardstick. If you like 10 shot groups as your yardstick, then great, that’s your yardstick.
Josh
Well-Known Member
It's all in what you like and are comfortable with, nothing is wrong, I just like math and statistics
RBHarter
West Central AR
I over layed every shot for a whole summer of paper targets on a single sheet from the first shot of every group centered on the transfer target . Almost every Saturday from 6/1 to 10/8 so 18 weeks , Saturday missed was usually covered up with a Friday and sometimes a Sunday too . 23 targets in all 5 shots each from assorted 2 or 3 point sitting or kneeling field positions. 115 rounds . Turns out I had a rifle , load , and operator that I could pretty well count on for 2.5" . Each individual 5 shot group was right at 1.25" CTC , not bad in a 40 yr old field rifle Savage 110 . Sometimes it would drift vertical from the first shot sometimes horizontal. The only pause of significance was to locate the first hole and shoot 4 more in a follow up way . The first 5 shots involved being mildly over caffeinated, fast walking to the backers , full run (as close as I get anyway , 22 sec 100 in HS so ....) back to the bench ,5 rounds in , get into shooting position, and shoot 5 rounds . The idea was to learn to shoot through the target surge . Now the bench targets were better , but I wanted to know if the package was going to work .
Bret4207
At the casting bench in the sky. RIP Bret.
I'm a 10 shot group guy. Not so much because of statistics or anything, but because I know in a 5 shot group I'm likely to pull at least one. 10 gives me a core group...well, hopefully anyway! 3 shot groups are only useful for making sure a scope/sight hasn't gone out of whack.
To each their own. A long as it's not a 1 shot group there should be info there that can be made use of.
To each their own. A long as it's not a 1 shot group there should be info there that can be made use of.
Petrol & Powder
Well-Known Member
I've shot some amazingly small groups, it's that second shot that screwed things up. 
Jokes aside, evaluating the performance of a particular rifle/load combination will always involve some degree of probability but we can get a pretty good grasp of that probability. A rifle/load combination that consistently places shots inside some known diameter at some known distance, is likely capable of repeating that level of accuracy on demand. And that’s all we’re really trying to accomplish. We want to know - Is it likely, that this combination is capable of placing a bullet inside some known diameter at some known range?
If a rifle & load combination consistently places 5 rounds inside a 1.5” circle at a given distance, then it is highly probable it will be capable of repeating that level of accuracy on demand. The same holds true if it consistently places 10 shots inside the same circle, or 7 shots, or some other number. Ultimately, the number of groups is more telling than the number of shots in a particular group.
The downside to using groups made up of a larger number of shots is it simply takes more time to shoot those groups while keeping the barrel temperature down and it consumes more ammunition per session. But it still provides useful data. So to each his own.
Jokes aside, evaluating the performance of a particular rifle/load combination will always involve some degree of probability but we can get a pretty good grasp of that probability. A rifle/load combination that consistently places shots inside some known diameter at some known distance, is likely capable of repeating that level of accuracy on demand. And that’s all we’re really trying to accomplish. We want to know - Is it likely, that this combination is capable of placing a bullet inside some known diameter at some known range?
If a rifle & load combination consistently places 5 rounds inside a 1.5” circle at a given distance, then it is highly probable it will be capable of repeating that level of accuracy on demand. The same holds true if it consistently places 10 shots inside the same circle, or 7 shots, or some other number. Ultimately, the number of groups is more telling than the number of shots in a particular group.
The downside to using groups made up of a larger number of shots is it simply takes more time to shoot those groups while keeping the barrel temperature down and it consumes more ammunition per session. But it still provides useful data. So to each his own.
Josh
Well-Known Member
This is a very "to the point" way of looking at things. A rifle is only a long range shotgun, what range are your pellets hit probability lower than you feel ethical with that load.
People pattern shotguns all the time, it's all about the cone of dispersion, I'm sure people pattern shotguns with only one shell, but if you're into shotgunning, you're patterning a few of each type of shell. Same concept.
RBHarter
West Central AR
Oh Lord ......shotguns ......
Harder actually is better .
Shotgunners are even weirder about patterns , range , application , pattern density , and all manor of manipulation of all the above . Heaven help if you show up on the range with a camo tape , bare spots in the bluing , dog dinged field gun .
Struggling a little getting some 7.7 up to speed .....
Harder actually is better .
Shotgunners are even weirder about patterns , range , application , pattern density , and all manor of manipulation of all the above . Heaven help if you show up on the range with a camo tape , bare spots in the bluing , dog dinged field gun .
Struggling a little getting some 7.7 up to speed .....
No camo tape, but a krylon painted, short 26" bbl, scratched up 11-87, with a sling on it. Love keeping up with the folks and their fancy shotguns on a trap/clays course...
fiver
Well-Known Member
my Win. 120 Trap gun has white and a turquoise-ish blue paint splattered on it.
i'm not gonna bother taking the paint off, but i would like to put a grip cap of some sort on it.
hmm, maybe the bottom of that Moose shed i have will be big enough, not like anyone is gonna steal it now.
i'm not gonna bother taking the paint off, but i would like to put a grip cap of some sort on it.
hmm, maybe the bottom of that Moose shed i have will be big enough, not like anyone is gonna steal it now.
Bret4207
At the casting bench in the sky. RIP Bret.
I stand corrected!