Over the years there have been a lot of different Load Development Methods used by reloaders.
Some simply make Random Selections from a Load Manual with no consideration given to Developing the Load from below. The Loads may do fine, but have the potential to either be Under Loaded – the rifle will not be able to take full advantage of the Cartridge, or when Over Loaded – the rifle will be subjected to Pressures which creates Cumulative Metal Fatigue. And of course, the majority of those Random Picked Loads will fall somewhere in between the two extremes.
Some reloaders go to elaborate lengths in an attempt to find the best load, but waste a lot of time, effort and components. They may shoot 5, 7 or 10 shot groups with a specific amount of Powder and may have 5-10 different Loads of that same Powder to Test. Testing only one Powder may take 1-5 days of shooting if they are allowing their rifle to cool properly between groups. Here again, they may or may not actually end up with the best possible Load for their specific rifle.
Frustration can set in and the reloader just accepts a Load that shoots OK rather than creating the best load possible for that specific rifle.
It is important to consider what is actually responsible for the Accuracy of the Final Load.
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 it’s unique Harmonics. And 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.
Thanks must go to Hotcore from accurate reloading for this article.
I hope this gives some useful help it certainly gave me some happy pointers.