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Eric Cortina and Hornady

Jayden said in the beginning of the video in order for the average of a gun to be a 1/4 min. gun at some point it had to shoot 1/2 min. That is not true at all. I personally shot these 3 - 10 shot groups recently with my 30BR. The agg. for the 30 shots is as follows

.325 10-SHOT GP
.198 10-SHOT GP.
.253 10-SHOT GP.
.776 TOTAL FOR 30 SHOTS
.258 AGG. FOR THE 3 10 SHOT GROUPS

The largest group my rifle shot was .325 and that is nowhere near 1/2 min group.
 
Last edited:
Bill Norris said:
Jayden said in the beginning of the video in order for the average of a gun to be a 1/4 min. gun at some point it had to shoot 1/2 min. at some point. That is not true at all. I personally shot these 3 - 10 shot groups recently with my 30BR. The agg. for the 30 shots is as follows

.325 10-SHOT GP
.198 10-SHOT GP.
.253 10-SHOT GP.
.776 TOTAL FOR 30 SHOTS
.258 AGG. FOR THE 3 10 SHOT GROUPS

The largest group my rifle shot was .325 and that is nowhere near 1/2 min group.
Click to expand...

Its just a matter of measuring things the same way. Measure the three groups as a composite and see what they measure. It'll be larger than the three groups measured individually
 
I was glad to see this thread title and will tune in. I’m very glad Erik is gathering all this top source information, and is letting people talk, with open ended questions.

I’ve been out shooting A-Tip 190’s and 250’s this afternoon at 600. This was my flattest group, coming from a 7 SAUM shooting with a constant hold.

Hornady, please don’t stop making these. Norma dropped my SAUM brass, Lapua “paused” more cartridge lines and I think misplaced all the yellow boxes I used to see, and I can’t get H-1000, because I’m not a bot.

1674260004898.jpeg
 
Bill Norris said:
Jayden said in the beginning of the video in order for the average of a gun to be a 1/4 min. gun at some point it had to shoot 1/2 min. That is not true at all. I personally shot these 3 - 10 shot groups recently with my 30BR. The agg. for the 30 shots is as follows

.325 10-SHOT GP
.198 10-SHOT GP.
.253 10-SHOT GP.
.776 TOTAL FOR 30 SHOTS
.258 AGG. FOR THE 3 10 SHOT GROUPS

The largest group my rifle shot was .325 and that is nowhere near 1/2 min group.
Click to expand...

I'm in the middle of the podcast now and I think I misinterpreted your question when I replied above. In the beginning of the video he's talking about the extreme group sizes (both small and large) you'd expect to see if you continued to shoot groups with a rifle that averaged 1/4 min.

My interpretation of what he was referring to was the normal distribution of group sizes. Backing up for a second, in their own podcast (Hornady) they discussed having fired many thousands of rounds in different tests but they found over and over that shot dispersion follows a normal random distribution, in other words it follows the basic bell curve we're all familiar with. So if you fired say 50 5-shot groups (in your case, with a gun that averages 1/4 min) and plotted the size of the groups, the distribution of groups sizes would follow the bell curve. Most of the group sizes will be towards the center but at the extremes there will be a few groups that measure 1/2 min on the big end and a few that measure very small (forgot what his number was exactly).

So those 3 groups that ranged from .198 to .325 are only 3 data points on the bell curve of group sizes. If you continued firing groups you'd start to see the bell curve fill in to the point that there would be an extreme large group and an extreme small group. It's theoretically possible but practically impossible for 3 random groups to represent the extreme small, extreme large, and the mean group size for that system.
 
TC260 said:
I'm in the middle of the podcast now and I think I misinterpreted your question when I replied above. In the beginning of the video he's talking about the extreme group sizes (both small and large) you'd expect to see if you continued to shoot groups with a rifle that averaged 1/4 min.

My interpretation of what he was referring to was the normal distribution of group sizes. Backing up for a second, in their own podcast (Hornady) they discussed having fired many thousands of rounds in different tests but they found over and over that shot dispersion follows a normal random distribution, in other words it follows the basic bell curve we're all familiar with. So if you fired say 50 5-shot groups (in your case, with a gun that averages 1/4 min) and plotted the size of the groups, the distribution of groups sizes would follow the bell curve. Most of the group sizes will be towards the center but at the extremes there will be a few groups that measure 1/2 min on the big end and a few that measure very small (forgot what his number was exactly).

So those 3 groups that ranged from .198 to .325 are only 3 data points on the bell curve of group sizes. If you continued firing groups you'd start to see the bell curve fill in to the point that there would be an extreme large group and an extreme small group. It's theoretically possible but practically impossible for 3 random groups to represent the extreme small, extreme large, and the mean group size for that system.
Click to expand...
You may be correct but knowing my rifle and loads I believe I could fire ten 10 shot groups and still maintain really close to that .258 agg. Maybe I will try that one day.
 
Last edited:
Bill Norris said:
Jayden said in the beginning of the video in order for the average of a gun to be a 1/4 min. gun at some point it had to shoot 1/2 min. That is not true at all. I personally shot these 3 - 10 shot groups recently with my 30BR. The agg. for the 30 shots is as follows

.325 10-SHOT GP
.198 10-SHOT GP.
.253 10-SHOT GP.
.776 TOTAL FOR 30 SHOTS
.258 AGG. FOR THE 3 10 SHOT GROUPS

The largest group my rifle shot was .325 and that is nowhere near 1/2 min group.
Click to expand...
Statistically speaking… If a guns average (mean) group size is .250 moa then over the course of its life it will shoot anywhere between .250 - 6SD and .250 + 6SD where SD is the abbreviation for standard deviation of the population mean. In this case we are measuring group size…. 67% of the time group size will be within +/- 1SD of the population mean where the population mean is the average of every group size fired from that firearm over that barrel’s life. The smaller the SD the narrower that spread. So to say that a gun has to shoot 1/2 min if it averages 1/4 min is really not statistically true without a lot more data. 1/2 moa max means 0 moa min on a perfectly normal data set - IE the data fits a Gaussian distribution perfectly (P value = 1)

Realistically there is enough erratic variation (shooter, accoutrements, atmospheric conditions, components, etc) to make the data non normal and therefore this model becomes extremely complicated as it doesn’t fit a normal distribution. Data will be more likely left or right skewed or potentially bi-modal in nature.

Crap I think I just talked myself into turning a new barrel and running a long term experiment.
 
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