The Firing Line Forums - View Single Post - Do you need at least 10 shots to establish a valid group?

rjinga · April 3, 2017, 04:53 PM

I think my actual Google search term was "What's the significance of the three-shot group?" Within the first few search results was this post: http://www.bealeinnovations.com/stats-3shotgroup.pdf

Now, I admit that I'm not a statistician/mathematician/engineer; however, other than kind of losing me with his three dimensional graphs, everything else he wrote about actual shot distribution seemed to make sense. And, I agree with his grandpa - hitting what you're shooting at is the point.

So, with that in mind, I ran my most recent 10-shot targets back through the OnTarget app to display the mean radius circle (drawn using the average distance of all the shots from the center of the group) and the group extent box (created by drawing intersecting straight lines through the center of the most outlying shots).

The rifle is a PTR 91 GI Classic; the ammunition is MEN 16 7.62x51. Unless otherwise noted, all the targets were shot from a table rest with the iron sights.

When shooting this target I was sitting on a small block and resting the barrel on a rail.

When shooting this target I was standing and using the sling.

April 3, 2017, 04:53 PM	#1
rjinga Senior Member Join Date: July 3, 2012 Location: N. E. Georgia Posts: 512	Do you need at least 10 shots to establish a valid group? I think my actual Google search term was "What's the significance of the three-shot group?" Within the first few search results was this post: http://www.bealeinnovations.com/stats-3shotgroup.pdf Now, I admit that I'm not a statistician/mathematician/engineer; however, other than kind of losing me with his three dimensional graphs, everything else he wrote about actual shot distribution seemed to make sense. And, I agree with his grandpa - hitting what you're shooting at is the point. So, with that in mind, I ran my most recent 10-shot targets back through the OnTarget app to display the mean radius circle (drawn using the average distance of all the shots from the center of the group) and the group extent box (created by drawing intersecting straight lines through the center of the most outlying shots). The rifle is a PTR 91 GI Classic; the ammunition is MEN 16 7.62x51. Unless otherwise noted, all the targets were shot from a table rest with the iron sights. When shooting this target I was sitting on a small block and resting the barrel on a rail. When shooting this target I was standing and using the sling. __________________ "Yo homie. Is that my briefcase?" Sig Sauer P229 SAS GEN 2 E2 9mm; PTR 91, GI model; Chinese Type 56 SKS; Smith & Wesson Shield 9mm