Use lowest SD or lowest MOA?

[SGK]

FWIW - for people who do want to use stats - that spreadsheet (as shown in David's posted pic - I've not downloaded the file) could be so much more. Inherently one is trying to determine whether there is a statistically significant difference between each of the tested loads. We can use David's data as an example. How confident can we be that the underlying behavior (in statistical terms, the 'population') of Load 2 is different from that of load 1 based on the samples of each? It can appear very easy to dismiss load 2 as being very different from (and worse than) load 1. But statistically we can only be 72% confident that this is so. That's not a particularly high level of confidence; confidence levels of 90% or 95% are more typical. It would take extra shots of each to gain greater confidence in the decision taken. Confidence levels can become a personal thing but at least it's good to know confident one can be that two things are different.

This calculator (and associated blog articles) is a very good resource for the statistically minded

https://www.autotrickler.com/stats-calculator.html

I wish I had a rifle and reloading techniques good enough to deliver such low SD/ES velocity stats.

 

[Texas10]

I'm guessing that you're not shooting a bare bones, stock Savage 12FV. I'm curious what improvements you've made. Care to share, maybe even some pictures?

 

[PDS]

Maybe some club could hold a chronograph championship. Awards for high velocity,low SD and highest confidence level.

 

[swd]

All the match’s I shoot the smallest group wins. Never been to one where they measured SD..

 

[fyrewall]

Stats like SD and ES with a 5 shot string will show up any really bad stuff but using those 5 shot stats is only a start in making final determination to what will be the best load.

 

[dmoran]

For LR (my main interest), I am of the opinion vertical dispersion trumps both velocity data and group size. And the further the distance, the more effect vertical has on group spread. Assessment and charting of it will statistically prevail in my experience, which I seldom see done (typically only see velocity and group size analysis). Vertical dispersion is significantly my primary assessment with all load development and tuning.

Reference image of one of the calculations spread sheets that I use when ladder testing:

 

[fyrewall]

For LR (my main interest), I am of the opinion vertical dispersion trumps both velocity data and group size. And the further the distance, the more effect vertical has on group spread. Assessment and charting of it will statistically prevail in my experience, which I seldom see done (typically only see velocity and group size analysis). Vertical dispersion is significantly my primary assessment with all load development and tuning.

Reference image of one of the calculations spread sheets that I use when ladder testing:

View attachment 1112634

The spread sheet looks impressive - lots of data in one place. I don't understand what the column starting with 0,000 and ending with 16,000 is.

 

[dmoran]

@fyrewall
An inch scale of the vertical dispersion to each shot.

 

[Alex Wheeler]

ES/SD does not directly correlate to group size at short or long range. Chasing ES once your under 20 fps or so is a waste of time. You can shoot 1" of vertical at 1k yds with 20 fps of ES. The perfect tune is what you should be after. The smallest groups at the range your shooting or the farthest range you will shoot.

 

[fyrewall]

@fyrewall
An inch scale of the vertical dispersion to each shot.

Got it - thanks for the speedy reply

 

[Milo 2.0]

Hello all, I am trying to improve my new reloading skills and have been shooting lots of groups with various combinations looking for a solid 140 g. performer. I think I just shot the best I can do, but question whether to go with lowest SD group or best moa group.
Two days ago at the range testing the 6.5 CM with 5 shot groups,
Using a LabRadar, the best results I got were:
42.3 gr H4350 - ES 7, SD 2.6, avg 2807 fps, .39 moa
42.6 gr H4350 - ES 10, SD 3.8, avg 2821 fps, .32 moa

My gut tells me to go with the SD 2.6 load and work on distance to lands. I appreciate your input, thanks

Bud

Some guys can make what you want to do work, not sure if by accident, luck, or if the method is proven. There can be some built in failure right from the start, an example would be, what do each of these groupings do at 1000 yards. If one or both now open up to .8 moa vertically, your numbers now mean diddly squat, as most here would agree the load is not really trustworthy for repeatable accuracy at distance.
Some of this crap, combined with that ab wez program, probability of hits has given many a false sense of security. Shrink target size and a lot of theories disappear fast.

Maintaining uniformity is my goal. The bullet seater I use for the 6.5 achieves the concentricity I expected, but the seating depths vary too much, in my mind. What are your thoughts on the Wilson seater w/micrometer to help get to the seating consistency? Hypothetically, all other variables staying the same on the above results, would .005" accuracy in seating depth improve ES/SD for 1000 yard shooting?

On this, you will want considerably better than a .005" variance in seat depth to do much at 1K, especially with a newer barre.

 

[dmoran]

..... would .005" accuracy in seating depth improve ES/SD for 1000 yard shooting?

Besides the seating die, base to ogive and/or base to seater stem diameter of the bullets has effects on seating consistency as well.
Myself strive for less then 0.001" from qualified bullets, and do not accept more then 0.001" variation (0.005" would be unacceptable to me).
My 2-Cents

 

[Dave Way]

Along the same lines as dmoran’s post, I first sort the lot of bullets base to ogive, then the loaded rounds base to ogive-on a well known Gunsmith’s recommendation. In effect you are looking for a difference in nose geometry as the Bob Green tool does. This is done after sorting the loaded rounds by seating pressure.

Before anyone speaks up with “I wouldn’t have enough matched rounds left for the target”, I don’t have that issue-I assume due to careful case preparation. For 50 rounds my seating pressure usually runs in a range from 20-24 PSI and the cartridge base to ogive varies no more than .0005” for 50 rounds which is how I sort them. This is a good lot of bullets.

Dave.

 

[Forrest Mc]

I'm guessing that you're not shooting a bare bones, stock Savage 12FV. I'm curious what improvements you've made. Care to share, maybe even some pictures?

Tex, Thanks for the interest. The only change to the 12 FV is bedding it into a Boyds ATOne stock. A Vortex Golden Eagle is on the 6.5. Here is a boring video

 

[Big_Daddy]

I shoot all of my load developments with my Lab Radar. Why....Because I am curious...LOL
In the end, the final load decision is based on the best consistent grouping combination for the purpose that I am loading for. It is just that simple for me.

 

[Forrest Mc]

Besides the seating die, base to ogive and/or base to seater stem diameter of the bullets has effects on seating consistency as well.
Myself strive for less then 0.001" from qualified bullets, and do not accept more then 0.001" variation (0.005" would be unacceptable to me).
My 2-Cents

.005 wasn't acceptable to me either. I did a couple of things to improve that: 1. New washers on the press to remove slop, 2. Smoothed out my ram stroke as well as softened up hitting bottom.
Since, I have been within that .001" reloading .223s to 1.8525" base to ogive using a micrometer seater. I haven't been measuring bullet, yet.

 

[Sixgun]

Shoot for ES/SD..and the groups with follow. If they don't than its human error or enviroment (wind, temperature) BTW..what distances that?

 

[Dusty Stevens]

Shoot for ES/SD..and the groups with follow. If they don't than its human error or enviroment (wind, temperature) BTW..what distances that?

Not in the real world. Ive never seen an impressive es/sd be close to the best load on paper where it matters.

 

[Sixgun]

Not in the real world. Ive never seen an impressive es/sd be close to the best load on paper where it matters.

If that's the case..than why does everyone strive for single digit ES/SD numbers?

 

[swd]

If that's the case..than why does everyone strive for single digit ES/SD numbers?

Because it seems like good logic. But the better logic is what the targets tell you. That’s where the rubber meets the road. I’ll take an extreme spread of 20 that holds X ring at 1K over an es of 4 that holds 10 ring every time.