Thread: Testing a conventional approach to load development

Gotta love gun nerds!! It certainly has been enlightening and given this has been bandied about in the gun world for years, good on Hornady for expending the barrels and ammo to shed some real data on the subject (and, of course, our posters as well) Back tracking this on the interweb, I found that as far back as the 1800’s, ten shot groups were the norm to average out accuracy, then slowly devolved to smaller and smaller lots over the decades. I’m sure there was some logical reasoning behind it.

It’s certainly been fascinating, thank you.

@gimp thank you for spending your money and time to bring us this data. As well as other the other data in recent related threads. It is extremely interesting.
I have listened to Hornady #50 podcast, will be also take in the follow up #52 podcast.
All of this explains a lot of personal observations of variability in my ( usually 3 shot ) groups. I also realize I've wasted soooo much time and ammo on "a couple of clicks" when sighting/checking zero using 3 shot groups and looking for differences group size based on small changes in powder weight.

I get a hint of confirmation bias in the initial abstract.

[QUOTE]. Go back to the range, shoot again, start trying to "fine tune" when the confirmation loads do not meet the same level of performance as the initial test
/QUOTE]

I would ask what happens when the confirmation loads do meet the initial test? I get the feeling the author is perhaps holding the idea that the initial test is the best group in the ladder. When speaking as a hunter reloader, the initial test is a group that meets the standard required. Which is I think something you will agree on.

So my process is to load up a ladder from somewhere above book minimum- because I know my rifle and load- and shoot till I approach book max. If all groups in the ladder are under my required standard of 1.25 -1.5 moa approx then I will simply choose the one that gives me the velocity im after with the least powder and im done.

If none or many are not achieving the standard I want then I will try a different projectile. If that does not work then I will replace the gun.

Originally Posted by Makros

Funnily enough, with these SD for each group, for an 80% power (80/100 times you test you will detect the statistically significant difference in mean group radius and reject the null hypothesis they are the same), you need at minimum 19 shot groups.

This is rather revealing when one group is 77% bigger and has a 66% larger mean radius than the other, it still takes at least 19 shots to be sure they're different, because of the quite large variance (SD) of the samples.

Just playing here:
Assuming consistent SD of group 1 = 0.38cm and SD of group 2 = 0.58. Required sample size to detect a few differences in mean radius are below.
0.1cm difference in mean radius = 379 shot groups
0.2cm = 96
0.3cm = 44
0.4cm = 25
0.5cm = 17
0.6cm = 12
0.7cm = 9
0.8cm = 8
0.9cm = 6
1.0cm = 6
1.1cm = 5
.
.
.
1.6cm = 3

Post script; nothing wrong with your stats assuming you're picking the t-test for unequal variances. It's the appropriate test.

Brilliant insight into the realm of statistics there!
Just shows it is ridiculous for the average shooter to bother being statistically confident in their load.

This is the reason why I'll stick to my load development techniques which are only 3-5shot groups, followed by multiple (different shooting sessions) 3-5 shot groups of whatever load I think has the best potential.
If they look good and sd's are acceptable, then I'll have confidence in the load/rifle. This will lead to confident shooting which is a major factor on the hill hunting or gong shooting.

The simplified approach. Same rifle 2209 147ELDM. Why? Better bullet, likely to actually be used from this rifle.

10 rd at 100m - acceptable for requirements. Speed 2600 avg as expected based on book data. .3 up .3 left to zero. SD fine as you expect with quality components.



3 at 300


3 at 400


At 500 (+) my hit probability is definitely dropping off on this small plate


I left home about 12, just got back. Load sorted

I sort of agree with STC.

I used to do load development. Nowadays I just load the max load with a decent bullet and if it doesnt lock the bolt up and the velocity is acceptable and it will shoot into an inch and a half, I am happy.

I dont see any difference between your approach and mine; although I produce less graphs.

What’s the barrel length of your 260 @gimp? I’ve got a model7 & 260 factory bbl that will be off to gunsmith shortly. Thinking to go 18in.

This rifle is something like 18-19 inches, I don't recall exactly

Sometimes you just have to use what is at hand. Some time ago I bought 300 rounds of Belmont 62 gn 223. Ive tried it in several rifles and none would shoot it well.

Today I was reviewing these last few "accuracy" threads and realized (Im probably a slow learner, beg your pardon in this is nothing new) maybe I could improve it.

Using the analysis tools to look at larger sample sizes I thought - maybe I can make this ammo usable. So I shot 3 groups of 5 shots on top of each other.

Then using BallisticX (but any of them will do the job) I analyzed the very average "group" and used its recommended offset to adjust the scope.

The result should be a very precise zero. This precise zero "improves" the ability of the combo to place shots on targets (fir this ammo, Wallabies and goats) at reasonable distances.

So the ammo is not wasted afterall.



Cheers

PS - bloody good shooting Gimp, well done!

Is that numbering in order of shots fired? If so I think you actually have something weird going on as it’s pretty clear the groups are walking up the page

Originally Posted by PerazziSC3

Is that numbering in order of shots fired? If so I think you actually have something weird going on as it’s pretty clear the groups are walking up the page

Nope. I just analysed them up the group

Originally Posted by Tentman

Sometimes you just have to use what is at hand. Some time ago I bought 300 rounds of Belmont 62 gn 223. Ive tried it in several rifles and none would shoot it well.

Today I was reviewing these last few "accuracy" threads and realized (Im probably a slow learner, beg your pardon in this is nothing new) maybe I could improve it.

Using the analysis tools to look at larger sample sizes I thought - maybe I can make this ammo usable. So I shot 3 groups of 5 shots on top of each other.

Then using BallisticX (but any of them will do the job) I analyzed the very average "group" and used its recommended offset to adjust the scope.

The result should be a very precise zero. This precise zero "improves" the ability of the combo to place shots on targets (fir this ammo, Wallabies and goats) at reasonable distances.

So the ammo is not wasted afterall.

Attachment 254237

Cheers

PS - bloody good shooting Gimp, well done!

I'm a slow learner as well...but now I see it...good post, great conversation.

Originally Posted by Tentman

Sometimes you just have to use what is at hand. Some time ago I bought 300 rounds of Belmont 62 gn 223. Ive tried it in several rifles and none would shoot it well.

Today I was reviewing these last few "accuracy" threads and realized (Im probably a slow learner, beg your pardon in this is nothing new) maybe I could improve it.

Using the analysis tools to look at larger sample sizes I thought - maybe I can make this ammo usable. So I shot 3 groups of 5 shots on top of each other.

Then using BallisticX (but any of them will do the job) I analyzed the very average "group" and used its recommended offset to adjust the scope.

The result should be a very precise zero. This precise zero "improves" the ability of the combo to place shots on targets (fir this ammo, Wallabies and goats) at reasonable distances.

So the ammo is not wasted afterall.

Attachment 254237

Cheers

PS - bloody good shooting Gimp, well done!

That's the hunting accuracy that's been talked about so much. Don't really have an excuse for missing much at conventional ranges with that

Had a crack at a 20 round group to get a better idea of my true zero and accuracy.
Blued Howa 1500, 308win, 20" sporter barrel, hs precision stock, Element Optics 2-16×50HDLR, Nikko Stirling zero-lok rings.
Shooting 165gn speer btsp's over ADI2208 in Sako brass.

5 shots then 5 minute break to let things cool down



Second lot of 5 shots (10 in total) then 10 minutes cool down.



Third lot of 5 shots (15 in total) then 10 minutes cool down.



Forth lot of 5 (20 in total)




I had one flier out to the right on it's own in the 3rd lot of 5 shots, I 100% know I pulled it I was getting uncomfortable and my back was spasming. It doesn't really matter but just worth mentioning. It was the first round of my 3rd 5 shot string, I got up and stretched after that and drilled the next 4 rounds back into the main grouping. I'm not trying to kid anyone or myself one outlier doesn't ruin that group.
20 rounds shot prone off my bipod 1.6" inside edge to inside edge is still plenty good and gives me a very good indication of my true zero.
Just want to say thanks @gimp your journey has been very compelling for me as a reloader.
Not bad for a $500 Howa in a flashy stock

100m or 100y? @dannyb