I found this post in another forum and thought it might be of help.

The Creighton Audette Precision Loading Method


Every rifle is unique in that there are minor variations in each component's material, manufacturing operations used during fabrication and assembly, attached sighting devices and shooter technique. Each has an influence on the Harmonic created when a cartridge is fired. When a person wants the best Accuracy possible, the trick is to use a Load Development Method which allows the reloader to quickly and accurately determine where the best Harmonics are for a specific set of components.

Harmonics are vibrations created in the firearm when a cartridge is fired due to multiple stresses placed on the barrel and action. It is helpful to think of the muzzle moving in an elongated Figure 8 during firing that can be leaning to the right or the left. Our goal is to develop the Load so the Bullet leaves the muzzle when the Harmonic oscillation is either at the Apogee or Perigee, when the muzzle has nearly stopped moving. That is because the muzzle movement slows as it approaches an end, nearly stops, changes direction, and then begins speeding up again. At the cross-over mid-point of the Figure 8, the muzzle speed is the greatest. Loads which cause the Bullets to exit the barrel during the highest amount of muzzle movement will create a larger group.

Barrel Harmonics can be controlled by a structured Load Development Method which allows the reloader to determine where the Harmonic Convergence, Clusters or Nodes are located. Then the Final Load is Fine Tuned by adjusting the Seating Depth.

There are additional Accuracy Tricks a person can use such as Fully Prepped Cases, match Grade Bullets, Partial - Full Length Resizing(P-FLR) and Seating Into-the-Lands. Each of which helps with the potential to develop a consistently Accurate Load for a specific rifle. (Some of the Tricks are excellent for Target shooting, but are best avoided for Hunting Loads.)

Though the same Load might shoot OK in a different rifle, the user is limiting the Accuracy Potential of the second rifle due to slight variations in its unique Harmonics.
A Load which is SAFE in one rifle may not be SAFE in another rifle - always develop a Load from below for each unique rifle.

The never improved upon, time tested Creighton Audette Method allows a reloader to locate the points of Harmonic Convergence with the least amount of components and time expended. The simplicity of Mr. Audette’s Method makes it usable by even novice reloaders and provides them the ability to achieve the best possible accuracy for their components with a specific rifle.



The Creighton Audette Method(aka Ladder Method)

1.After selecting specific components for Testing, reload a series of individual Cases with an incremental increase in Powder.
2.Fire each individual Load onto a single Target at 300 yards.
3.Note the specific Point of Impact for each test cartridge.
4.Look at the Targets to determine where there are shot clusters and note the specific amounts of Powder. These are the points of Harmonic Convergence.
5.Reshoot Loads Developed around the Clusters to verify the Final Load.

That is all there is to it. Simple and uses the minimum amount of components possible to find the best possible accuracy for them in a specific rifle.

Here are some additional tips to help get a person started:

1.Always watch for the normal Pressure Indicators as the Test Loads are being fired. Just because a Load is shown as SAFE or below MAX in a Manual(s), does not necessarily mean that applies to ALL RIFLES chambered for that Cartridge.

2.When selecting the amount of variation in the Powder, use 0.2gr in small cases(223Rem, etc.), 0.3gr in medium cases(308Win), 0.4gr in large cases(30-06), and 0.5gr in magnum cases(300WinMag). Do not start below or go above Loads shown in 2-3 Manuals.

3.There may be two points of Harmonic Convergence on a single Target. Focus on the group using the most Powder for the best on-game performance.

4.Reload a series of three 3-shot groups to Verify the point of Harmonic Convergence. Shoot them on individual Targets and then stack the targets and look at them with a strong light behind them to see if they are remaining in the same spot.

Example: You look at a Target and notice Test Loads with 40.0gr, 40.3gr, 40.6gr, 40.9gr and 41.2gr have progressively gotten closer together and then began widening again. They seem to Cluster around the 40.6gr load. So, you load three Test Loads at 40.3gr, three at 40.6gr and three at 40.9gr and shoot them into individual Targets.

5.Shooting at Dawn and Dusk typically provide some of the calmest wind periods.

6.Shoot quickly enough that there is less change in the environmental conditions, without overheating the barrel.

7.If possible, use a person to Spot the Points of Impact with a large Spotting Scope. It is also possible to use a second person Down Range to mark the Points of Impact, but can be dangerous if done in a casual manner.

8.For short range firearms(30-30, 35Rem, 44Mag), the Targets should be shot at 100yds. For other cartridges, shooting at 300yds allows the Clustering to be more visible than when shot at 200yds. But, if 300yds is not available, 200yds can work.

9. Once a Load is developed around a Harmonic Cluster, it is possible to further Fine Tune the Load by testing various Seating Depths.

10.Make Targets with a 4"-6" Black Square and shoot at a corner.

11.Take a few Spotter Rounds to get you onto the 300yd Target to begin with so the actual Test Loads are not wasted.

12.Focus on the Target so your concentration is at a peak. If you do flinch on a shot, be sure to note it on your Load Data Sheet.

13.Benchmark the rifles best possible accuracy to start with, using Match Grade bullets Seated to just Kiss-the-Lands or 0.005"-0.010" Into-the-Lands.

14.Once you know the accuracy potential of the rifle, begin Load Development with the Hunting Grade bullet you intend to use.

15.Take cleaning equipment with you to the range and use it. Some bullets foul a barrel much worse than others and trying to develop a Load with a lot of copper in it does not represent the barrel condition you will be hunting with. So, clean it at the range as appropriate.

The 1st Test Cartridge has 43.0gr of Powder in it and after getting in a good solid position you shoot it at the Target. You look through a good high power Spotting Scope and mark on a Target next to you where that "1st" shot hit.

The 2nd Test Cartridge has 43.3gr of Powder in it and after getting in a good solid position you shoot it at the "same" Target. You look through a good high power Spotting Scope and mark on a Target next to you where that "2nd" shot hit.

The 3rd Test Cartridge has 43.6gr of Powder in it and after getting in a good solid position you shoot it at the "same" Target. You look through a good high power Spotting Scope and mark on a Target next to you where that "3rd" shot hit.

Continue with the test until you reach the max powder limit or see Pressure Indicators - which ever comes first - and STOP. When you get through, some of the Test Loads will show holes in the Target "closer together" than the other shots and those are the Harmonic Clusters. That indicates those particular Loads had the Bullets exiting the muzzle when it was at an Apogee or Perigee.



As you look at the Target you see a Harmonic Cluster forming around
shots 9, 10, and 11. (See link. Target is at the bottom of this page)


http://wssmzone.com/main/default.aspx?c=reloading&c2=re...elopment&n=reloading


Once you see where the Cluster is forming, you go back and shoot a series of Test Loads made with those Powder levels to find the most accurate group. I use 3-shot groups at each Load Level on separate Targets, but you should use whatever you want.


Let’s say shot #10 group of 3 shots ends up being the most accurate group with 46.7gr of Powder with a specific bullet.

Then, fine tune the 46.7gr Load by adjusting the Bullet Seating Depth in .005 increments and reshooting to find greatest accuracy.

Mspingy, IMO this is the text of Hot Core, perhaps a bit modified here and there.
Succes on your development and let us know!
J.

This "ladder" business is called different names and there are several variations.

As I have stated on other "ladder" threads, no one doubts that barrel harmonics affect accuracy, however, it's a lot more complicated that the ladder advocates would have us believe.

For example, none of these ladder procedures recognize the need for statistical analysis of the results. One string of powder increments proves nothing, statistically speaking. Repeating the test still proves nothing, statistically speaking. To even begin to prove anything you will need to repeat the test at least five times, and even 5 data points is marginal. So instead of being a simple quick method, you'll end up doing a whole lot of shooting, just like any other reloading technique.

Obviously, there are other things that effect accuracy beside harmonics, and there are other ways to optimize the harmonics besides changing the powder level.

I am not opposed to the ladder method, I'm just saying it's not as simple as some would have us believe.

At the risk of getting yelled at, I submit you might want to check out another system that's a bit easier to use and works quite well. Do a search on this forum for "OCW" or go here.

Hi Crimp. Dan Newberry sent me this same info that you posted in your reply. It is another method worth checking out.Thanks for your input.

I've tried the ladder system, but I didn't have a 200 or 300 yard range. I wasn't impressed with results at 100 yards. I'm not ruling out retrying it, but I like theory behind the OCW system. Easier to use @ 100 yards.