Little Crow Gunworks: Avg POI Is More Important Than Group Size. Thoughts?

[WeR0206]

This might be a bit controversial but he makes some good points. You need to look at both precision (mean radius/ES) and accuracy (API). To give some context his load development process he does use group size but its not the main focus.

He starts with testing 2-3 different powders with his desired bullet for the use case. For 308 he will use gordons reloading tool to find the charge weights for 50K to 62K and go in .2gr increments and load one shot at each increment. He will do this process for each powder then shoot 10-15 round groups (a single POA for each powder). The point of this is to see how temp/pressure sensitive each powder is.

Here he tested 3 powders:

He Id’d powder C as the best (look for group size < 2”) then repeated the same charges for powder C as step 1 but 3 shot groups for each increment instead 1.

The red numbers represent different temps. Look for 4-5 charge weights in a row that have similar API and low vertical stringing and the target in the middle will be your charge (see stars)

Here’s a nice AI summary of differences between mean radius and API:

 

[ShtrRdy]

That's pretty much how Optimal Charge Weight method works.

 

[patriotnation]

I have watched this whole series and it has confirmed much of what I know and do, while also learning a lot. It makes sense to me that before group size, you must consider POI first. After all, what good is that one tiny group if it is much farther away from your point of aim?

 

[ma smith]

This is statistics 101. You would only use the ES to "guess" the mean radius.

 

[WeR0206]

I have watched this whole series and it has confirmed much of what I know and do, while also learning a lot. It makes sense to me that before group size, you must consider POI first. After all, what good is that one tiny group if it is much farther away from your point of aim?

+1 on this. I think his series of reloading videos is fantastic so far. For example I had no idea gordons reloading tool even existed and its so helpful.

 

[patriotnation]

Yep, it convinced me to download it and learn to use it.

 

[memilanuk]

I'll admit, I'm probably - no, *definitely* - guilty of 'deciding' on the powder/bullet based on factors other than actual testing, and then trying to 'make' them shoot. In my defense, that was usually because a) I was shooting some combos that were pretty well mapped out by others (308/223 + Varget + pretty much any bullet, or 6CM / 6.5CM + H4350), or b) there were external 'requirements' (team sponsors, etc.).

That said, I am intrigued by both the way he uses GRT to filter/winnow the powder options, and doing the aggregate ladder test to explore the overall grouping tendency of the selected powders. I might have to tinker with that some myself.

The other bits about POI vs raw group size are, as others have pointed out, is basically OCW redux... but he does a good job covering how/why the POI moves and what to actually look for.

 

[richthe1]

Is finding a “node” a legit thing or no? I could be remembering wrong, but I feel like he says yes and Brian Litz says no?

 

[memilanuk]

All the videos are free for the watching on YT.