WOW! You are a gem to this place! Thank you for that post.For posterity......or for anyone that cares.
5/5/2020: "off the shelf" copper creek loaded 140 Berger Elite Hunter out of a 22" Bartlein
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Median 3-shot group is 0.399 MOA
Median 5-shot group is 0.557 MOA
Overall 20-shot group is 1.023 MOA (with called flier); 0.78 MOA (excluding called flier)
The theoretical statistical factors are within percentage points of this real life exercise. Any discrepancy is likely due to shooter error and/or sample size.
As an aside, if people are interested in having quality data, they need to be able to call shooter errors. You can't discard a shot just because you don't like it, you can't keep a knowingly bad shot either (regardless of where it landed). In the above example, the statistical factors actually back-up the called flier.
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7/24/2020: Factory Prime 130 OTM out of a 26" Benchmark
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Median 3-shot group is 0.309 MOA
Median 5-shot group is 0.410 MOA
Overall 20-shot group is 0.650 MOA
The theoretical statistical factors are within percentage points of this real life exercise. Any discrepancy is likely due to shooter error and/or sample size.
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8/25/2022: Factory Hornady 108 ELDM out of 26" SS Proof barrel
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Median 3-shot group is 0.309 MOA
Median 4-shot group is 0.534 MOA
Median 5-shot group is 0.601 MOA
Median 10-shot group is 0.790 MOA
Median 20-shot group is 0.906 MOA
Overall 30-shot group is 1.085 MOA
The theoretical statistical factors are within percentage points of this real life exercise. Any discrepancy is likely due to shooter error and/or sample size.
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I'm being told that's 10 photos, but that's 3 different barrels using 3 different factory ammo. I’ve gone through that exercise many times over the last several years with different barrels & exclusively shooting factory ammo. I've used some boutique ammo suppliers, but I've never tried the "tuning" packs. I’ve posted several other of these 20 – 30+ shot groups on here, and some I don’t go through the effort of posting on here. The theoretical statistical factors are based on a normal distribution, and I’ve found those factors to be generally applicable to the barrels & ammo that I use.
As part of this exercise, I also track zero location relative to round count as I’ve been interested in how many shots I should really be using to achieve an appropriate zero. Based on the barrels & ammo that I use, I’ve found that 5 – 7 rounds gets me an adequate zero, and there really isn’t anything to gain beyond that. Even after these 20 – 30 shot “dot drills” I continue to compare (and sometimes aggregate) data from subsequent smaller round count groups. For my uses, there is not a significant difference between a 5-7 round group zero and a 30+ round group zero – meaning I cannot dial or hold the difference through the supersonic range. As much as I don’t like saying it, you can do a lot with a 3-round group in terms of zero. Of course, an inexperienced shooter and/or someone using substandard gear will do more harm than good with a 3-shot group.
I've also received some PMs over time, and I've taken a look at data from other members that would perform a similar "dot drill" exercise. An interesting trend I've noticed is that group zero location tends to get further from aggregate center from about 5 - 10 rounds(ish) and then converge back from about 10 - 15 rounds(ish). A likely cause could just be shooter fatigue/attention, but it's interesting to see the trend of larger round counts corresponding to poorer data.
It's also worth noting that if you are solely considering group ES, larger round count groups are probably not the way to go since you lose a ton of data resolution and you're making decisions based on 2-data points. A 30 round group is not the same as 30 rounds that are individually tracked (like I'm doing in the above examples). Shooting several smaller round count groups is likely a better way to go for most people if you want to work with good data.
I'm not advocating that anyone shoot 3-shot groups or 500-shot groups or anything in between. I'm just sharing data/experience, what works for me as a nobody/hobbyist in real life, and the why behind it.