10 Round Load Development Ladder method

[Melnic]

I was intrigued by this post in the 223 Precision thread
https://www.mdshooters.com/showpost.php?p=6588319&postcount=24

Which mentions this link:
http://www.65guys.com/10-round-load-development-ladder-test/

So, I borrowed a magnetospeed from a friend and tried it out today.
After getting the spacing sorted out (very important) I tested a 10 group .1 spaced ladder centered around my 223 precision 69gr SMK load.
I was delighted to see a velocity flat spot.
I used sorted GECO and LC cases which are only a couple grains apart in case weight.

I know this, if I were to do a 10 round test, I'd want to do it more than once. In this case, both agree'd with the flat spot, but noticed the wack LC load @ 23.1gr

I looked back at my pics/notes from when I did OCW (optimum charge weight) and the variation in group centering was pretty close in this flat spot range but I picked 23.5 based on the group size of 3 and now I can see, maybe I should have picked 23.6 or 23.7gr

 

[dist1646]

View attachment 337077

This was with 23.8 gr 8208 and 69's @ 200yds prone w/ sling. I have been thinking about backing it down a tenth of a grain or so to see if it does any better. You may be on to something.

 

[85MikeTPI]

I typically shoot for "minute of steel" and not so worried about precision, but since starting the precision 223 thread I'm
back to powder trickling rounds by the dozens, instead of the 1000s... I have a magnetospeed at the cabin and
plan on trying this as well..

 

[Speed3]

I've done the exact method and it works well. Based on the above chart 23.7gr looks like the winner. Allows for .1gr either way and still be in that node/window. .1gr variance isn't abnormal for most scales anyway.

You can further development by changing seating depth .003" at a time depending of loading to mag length(2.260 I think but been a while).

 

[holesonpaper]

I’ll agree with Speed. I like 23.7.. little variation and mostly indifferent to case..

 

[Melnic]

What has me a little bit puzzled is when I spent all kinds of hours reading about finding a "load" for a rifle, they all talk about harmonics and barrel movement and tuning it to the "calm" load. I just wonder if that coincides with a flat velocity curve or not?

I worked up 10 of 308 loads with my hunting bullet cause I want to get that consistent at 200 & 300 yards.

 

[Speed3]

What you are trying to achieve is consistency in the most accurate way. You don't want to find an oddball load that shoots one hole but if your seating depth is off .001 or the temps change 20 degress it shoots 1.5 MOA.

Ever wonder why FGMM always shoots in every gun? Federal spent lots of time finding those "wide" nodes that shoots well in sloppy or tight chambers.

 

[Doco Overboard]

What has me a little bit puzzled is when I spent all kinds of hours reading about finding a "load" for a rifle, they all talk about harmonics and barrel movement and tuning it to the "calm" load. I just wonder if that coincides with a flat velocity curve or not?

I worked up 10 of 308 loads with my hunting bullet cause I want to get that consistent at 200 & 300 yards.

Save yourself some time and just go on Amazon maybe, then purchase the Textbook of Small Arms 1929.
Its all in there,along with many available mathematical formulas provided by the stone age engineers and scientist.
They were busy solving problems for intercontinental warfare, not getting you tube hits or peddling merchandise.

 

[Magnumite]

I do not know if they still do, Hornady used this method in their load development tables. There was an explanation of it in the front of their loading manual.

I used it a few times as a “where to pay closer attention” determination.