Getting accurate poi and group size for 30 round groups

[HighUintas]

Hopefully this weekend, I'm going to get a 30 round group poi established.

I've been wondering about the most efficient way to get an accurate poi and group size for those 30 rounds, whether it is by using an app or by manual measurement of the target.

I currently use the Range Buddy app occasionally for getting poi, but it is hard for large round counts due to some rounds going through a preexisting hole and not being able to tell the actual poi of some rounds. So I've done multiple 5 rd groups and then averaged the POIs but then I have to do more work in finding the overall group size/extreme spread.

Is there an app where I can load a picture (s) of several individual 5rd groups, then have the app tell me the avg poi of all groups as well as the composite group size/extreme spread?

 

[Caseknife]

Could you use something like an A-17 NRA smallbore target and shoot three rounds at each bull? Would be easy to determine group size and POI. Just a 10 shot group gets to where you can't determine where the last few shots landed. Know there are down range camera set-ups that will record the individual impacts, but can be spendy.

 

[HighUintas]

Could you use something like an A-17 NRA smallbore target and shoot three rounds at each bull? Would be easy to determine group size and POI. Just a 10 shot group gets to where you can't determine where the last few shots landed. Know there are down range camera set-ups that will record the individual impacts, but can be spendy.

Yea, that's similar to what I was attempting to explain. For example, the targets below are one I did awhile back, but had to figure up the 30 shot composite poi and ES manually, which was a pain. I'd like to be able to put that picture in an app, mark the impacts and bulls, and have the thing calculate it for me.

I'm just trying to be lazy

 

[Formidilosus]

Hopefully this weekend, I'm going to get a 30 round group poi established.

I've been wondering about the most efficient way to get an accurate poi and group size for those 30 rounds, whether it is by using an app or by manual measurement of the target.

I currently use the Range Buddy app occasionally for getting poi, but it is hard for large round counts due to some rounds going through a preexisting hole and not being able to tell the actual poi of some rounds. So I've done multiple 5 rd groups and then averaged the POIs but then I have to do more work in finding the overall group size/extreme spread.

Is there an app where I can load a picture (s) of several individual 5rd groups, then have the app tell me the avg poi of all groups as well as the composite group size/extreme spread?

It is way simpler and better to just shoot all 30 on the same POA.

 

[HighUintas]

It is way simpler and better to just shoot all 30 on the same POA.

How are you determining the POI when you end up with 1 large gaping hole after 30rds and can't determine where the individual impacts are? Are you just using the very center of that hole for anything that falls inside it?

Sorry, I don't have any pictures that would help explain it, so hopefully what I am saying makes sense.

 

[Formidilosus]

How are you determining the POI when you end up with 1 large gaping hole after 30rds and can't determine where the individual impacts are? Are you just using the very center of that hole for anything that falls inside it?

The individual impacts don’t matter when it comes to the true cone- which is what size target you/it can hit. Shoot 30 rounds in whatever order you prefer, draw a circle that encompasses every shot- the center of the circle is your mean point of impact. The total diameter of the circle is your true precision ES.

 

[HighUintas]

The individual impacts don’t matter when it comes to the true cone- which is what size target you/it can hit. Shoot 30 rounds in whatever order you prefer, draw a circle that encompasses every shot- the center of the circle is your mean point of impact. The total diameter of the circle is your true precision ES.

Thanks for the explanation. That doesn't completely jive with the way I'm thinking about my crappy shooting causing a distribution that is not normal, but I'll take that advice and run with it.

 

[Formidilosus]

Thanks for the explanation. That doesn't completely jive with the way I'm thinking about my crappy shooting causing a distribution that is not normal, but I'll take that advice and run with it.

What are you seeing that’s an issue?

 

[HighUintas]

What are you seeing that’s an issue?

My thoughts behind determining mean poi for 30 shots are that it should include each shot's individual position because my shooter induced error likely prevents the 30 rd group dispersion pattern from being a normal distribution (more or less a circle/cone with higher shot density at very center). My error may cause the dispersion pattern to have most shots clustered around the bull's center but a few of them to be 0.5 mil left.

So I'm thinking of a calculated mean poi versus the center of a circle that contains all my shots. Those two locations could be very different.

Now.... Does it matter? Maybe it doesn't because with 30 rounds I'd have high confidence that 95% of my shots would land in that circle, so I should just go with the easiest method. But, I don't know

 

[eoperator]

Bullets make very small holes on the impact side of conveyor belt. I am willing to bet bet 30 impacts could be spotted to assess accurately as you are looking for.

 

[huntnful]

My thoughts behind determining mean poi for 30 shots are that it should include each shot's individual position because my shooter induced error likely prevents the 30 rd group dispersion pattern from being a normal distribution (more or less a circle/cone with higher shot density at very center). My error may cause the dispersion pattern to have most shots clustered around the bull's center but a few of them to be 0.5 mil left.

So I'm thinking of a calculated mean poi versus the center of a circle that contains all my shots. Those two locations could be very different.

Now.... Does it matter? Maybe it doesn't because with 30 rounds I'd have high confidence that 95% of my shots would land in that circle, so I should just go with the easiest method. But, I don't know

Easier/Simple is better in this instance I would say. If you want a 30 round group, just shoot one. You're interference with the impacts by getting on and off the rifle, are part of that group. As well as how you'll shoot in the field. It honestly isn't that critical. Get a zero, and start shooting at longer ranges to really assess your abilities.

 

[ElPollo]

My thoughts behind determining mean poi for 30 shots are that it should include each shot's individual position because my shooter induced error likely prevents the 30 rd group dispersion pattern from being a normal distribution (more or less a circle/cone with higher shot density at very center). My error may cause the dispersion pattern to have most shots clustered around the bull's center but a few of them to be 0.5 mil left.

So I'm thinking of a calculated mean poi versus the center of a circle that contains all my shots. Those two locations could be very different.

Now.... Does it matter? Maybe it doesn't because with 30 rounds I'd have high confidence that 95% of my shots would land in that circle, so I should just go with the easiest method. But, I don't know

I’m glad you are shooting big groups to get a handle on your cone of fire. But be happy with your 30-round group size, adjust your point of aim based on the center, and go practice wind calls in broken terrain. Your wind calls are, in all likelihood, a much larger source of variation than minor changes in assumptions or measurement methodologies for your 30-round group size.