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Originally Posted By HighpowerRifleBrony: My TL;DR: With a good rifle/ammo combo and no changes, even on different days with slightly different conditions, point of impact will remain true. If POI is significantly different, something probably went wrong or is not optimal, maybe the ammunition's load, the barrel, the sights, the weather, or that particular combination together. Three shot groups are not statistically significant: http://www.ar15.com/forums/t_3_118/279218_.html. More rest time (or for some folks, less time to think) between shots may be required to reduce the human factor. Originally Posted By HighpowerRifleBrony: Originally Posted By 1saxman: What is the point? You are an excellent shooter and you have a nice set-up. Do you mean to illustrate the variability of shots due to mechanical reasons or is it more about the human factor? I know with me it's the human factor. It's about all I can do to calm down and shoot three shots as carefully as I can - but when I do, results are good, and groups are small enough to be meaningful for scope adjustment if needed. Perhaps you could just add a sentence at the end of your articles summing up your conclusions. It would be very helpful to the AD types like me who basically skim articles like that. My TL;DR: With a good rifle/ammo combo and no changes, even on different days with slightly different conditions, point of impact will remain true. If POI is significantly different, something probably went wrong or is not optimal, maybe the ammunition's load, the barrel, the sights, the weather, or that particular combination together. Three shot groups are not statistically significant: http://www.ar15.com/forums/t_3_118/279218_.html. More rest time (or for some folks, less time to think) between shots may be required to reduce the human factor. If you fire 3 shots one day, and three shots the next, etc. you may find a different POI. But when all of those shots are all overlaid together and an average dispersion, or mean radius, or whatever, is found, THAT is the true POI. |
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Originally Posted By bfoosh06:
Molon..... Quote..."I fired three “seasoning rounds” of the Black Hills 69 grain Sierra MatchKing ammunition to condition the bore of the Lothar-Walther barrel with the powder used in this factory load. This process was repeated immediately prior to shooting each of the groups evaluated for this exercise. " Years ago ... I read an article about which powders you shouldn't fire after another type/brand, because it would cause accuracy issues briefly for the first few rounds ( CMP or High Power type shooting ) ... your "seasoning rounds" comment got me thinking about it again. Are you aware of such a list ? How do the seasoning rounds actually work ? ...or is it just something that should be done ? Generally speaking, it's when switching from ammunition charged with ball powder, to ammunition charged with extruded powder and vice versa. I just always do it whenever changing loads in the same shooting session. ... |
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Originally Posted By Currently:
Thank you Molon for taking the time to document your hypothesis and sharing them with us. YOU are one of the main reasons I pay for a membership to this site. De rien. 
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All that is necessary for Trolls to flourish, is for good men to do nothing.
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In God We Trust. Everyone else must post data.
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Originally Posted By Stickman: Yet some people and manufacturers continue to tout their 3 round groups as the actual accuracy of their barrels/ weapons. Please keep showing what you do, and don't let the haters push you away. Clown action gets pretty rough around here sometimes.  |
living well is the best revenge!
ETERNAL R & R my brothers
CPT Ritz,
SSG Epps,
SSG Ortiz,
LTC Rennie Cory Jr...
C co 2/325th ABN INF. 83-86
ETERNAL R & R my brothers
CPT Ritz,
SSG Epps,
SSG Ortiz,
LTC Rennie Cory Jr...
C co 2/325th ABN INF. 83-86
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Originally Posted By WeimaranerDad:
I don't know if this would be helpful or not...back in the early 1990's when I was at USAFA, I had to take a probability ands stats class taught by the Math deparment. If I am remembering correctly, we calculated Circular Error Probability (CEP). Just now doing some googling, I found this .pdf that relates to rifle shooting and CEP: http://www.google.com/url?sa=t&source=web&cd=8&rct=j&q=how%20to%20calculate%20circular%20error%20probable&ved=0ahUKEwikwa2Xw8LKAhXKmIMKHcECBacQFgg2MAc&url=http%3A%2F%2Fwww.statshooting.com%2Fpapers%2Fmeasuring-cep-mcmillan2008.pdf&usg=AFQjCNHNn73If3ZyqQ1LADbQsxSWmF1vxw Maybe that would be of help to somebody. That's a really good read, thanks for putting it up. |
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Originally Posted By azoutdoorsman: With enough shots fired, the true POI becomes apparent. If you fire 3 shots one day, and three shots the next, etc. you may find a different POI. But when all of those shots are all overlaid together and an average dispersion, or mean radius, or whatever, is found, THAT is the true POI. Originally Posted By azoutdoorsman: Originally Posted By HighpowerRifleBrony: Originally Posted By 1saxman: What is the point? You are an excellent shooter and you have a nice set-up. Do you mean to illustrate the variability of shots due to mechanical reasons or is it more about the human factor? I know with me it's the human factor. It's about all I can do to calm down and shoot three shots as carefully as I can - but when I do, results are good, and groups are small enough to be meaningful for scope adjustment if needed. Perhaps you could just add a sentence at the end of your articles summing up your conclusions. It would be very helpful to the AD types like me who basically skim articles like that. My TL;DR: With a good rifle/ammo combo and no changes, even on different days with slightly different conditions, point of impact will remain true. If POI is significantly different, something probably went wrong or is not optimal, maybe the ammunition's load, the barrel, the sights, the weather, or that particular combination together. Three shot groups are not statistically significant: http://www.ar15.com/forums/t_3_118/279218_.html. More rest time (or for some folks, less time to think) between shots may be required to reduce the human factor. If you fire 3 shots one day, and three shots the next, etc. you may find a different POI. But when all of those shots are all overlaid together and an average dispersion, or mean radius, or whatever, is found, THAT is the true POI. Great point, and it's another reason shooting a 10-shot string after walking in a zero is a good exercise. It really shows you if your POI is true to your POA. |
RIP WMD :(
"Some hills are not worth dying on and internet drama is one of them.." - a wise man I call sir
"Some hills are not worth dying on and internet drama is one of them.." - a wise man I call sir
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Originally Posted By winddummy82:
Originally Posted By winddummy82:
Originally Posted By Stickman:
Yet some people and manufacturers continue to tout their 3 round groups as the actual accuracy of their barrels/ weapons. Please keep showing what you do, and don't let the haters push you away. Clown action gets pretty rough around here sometimes.
We need to petition GB to get a "Clown Action" emoticon added to the website. 
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All that is necessary for Trolls to flourish, is for good men to do nothing.
In God We Trust. Everyone else must post data.
In God We Trust. Everyone else must post data.
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Originally Posted By azoutdoorsman: If you fire 3 shots one day, and three shots the next, etc. you may find a different POI. But when all of those shots are all overlaid together and an average dispersion, or mean radius, or whatever, is found, THAT is the true POI. Exactly, as well as the true precision of that rifle/ammunition combination. Here's an example illustrating the point. Using one of my AR-15s that has a free-floated Colt HBAR, I fired five, 10-shot groups from 100 yards using a hand-load topped with 55 grain FMJ bullets. The five 10-shot groups were over-layed on each other to produce a 50-round composite group with a mean radius of 0.70”. The average extreme spread for the five 10-shot groups was 2.30". Attached File I then proceeded to fire another 50 rounds of the same hand-load in 3-shot groups, for a total of sixteen, 3-shot groups (with an extra 2-shot group at the end.) Several of the groups were sub-MOA. group #06: 0.66” group #12: 0.92” group #13: 0.59” group #15: 0.41” group #16: 0.63” However, several other groups had extreme spreads of well over 2”. group #02: 2.53” group #07: 2.89” group #08: 2.39” group #09: 2.86” group #11: 2.47” Those who espouse the use of 3-shot groups for evaluating the radial dispersion of a rifle/ammunition combination like to point to the smallest 3-shot groups for their accuracy claims and then pretend that all those large 3-shot groups don’t exist. The average extreme spread for all sixteen of the 3-shot groups was 1.72”. Also, the statistical centers of many of the groups, (both large and small) were located at different locations on the target. Pictured below is the first 3-shot group of the 55 grain FMJ load and beneath that the first three, 3-shot groups over-layed on each other. Attached File Attached File As we continue to sequentially over-lay the 3-shot groups on each, the pieces of the puzzle begin to fill in the gaps giving us a more complete view of the entire picture. Attached File Attached File Attached File Finally, when all of the 50 rounds fired in 3-shot groups have been over-layed on each other, we have a composite group that is remarkably similar in radial dispersion to the 50 round composite group formed from the five 10-shot groups. Attached File Attached File Here’s the only target from the above shooting session that the Internet Commando would have posted. Attached File Remember, all the data for the above examples were obtained during live-fire testing from my bench-rest set-up, not from computed generated models that fail to demonstrate a correlation with actual real-world data. .... |
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Originally Posted By azoutdoorsman:
Hey look, an ACTUAL MOA barrel
A running thread on the accuracy of control groups fired from this barrel . . . Observations on the Accuracy of a 20 Lothar Walther AR-15 Barrel ... |
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