Ysterhout Dot Net
To fast track yourself to precision reloading
This appears very useful. The concept is proven by many, and the results seem to be repeatable, which ladder tests are not.
Although around a long time, it's not disproven or superceded yet. Click through to Dan Newberry's OCW website.
It seems to be a quick, reliable way to determine the optimum powder charge for the cartridge, using your components, and from there it's just seating depth and / or neck tension work.
Once the optimum charge weight range is found, and you settle on a charge, map the change in seating depth to the change in group size to find what is optimum for your load.
If your OCW is good and repeatable, but your ES and resulting groups refuse to shrink with seating depth changes, you can try a powder that gives a 100% burn in your barrel length, for your bullet weight. Gordon's Reloading Tool or Quickload are required for this.
In the past I stated that you could increase neck tension 1 thou at a time, and the ES should stabilise or improve, which it may, but it will not achieve the low variation as possible from a complete powder burn.
With a 100% powder burn rate, the neck tension does not need special treatment.
It may happen that the powder that gives a 100% burn also leaves too much air in the case, as it may have say a 90% case fill. For example, using 155 grain NCC in 308 Norma with N150 gives 100% burn rate and 90% fill. N160 gives 90-ish % burn rate and 100% fill. Case fill or burn ? Use dacron to take up the air space. One half of a grain of dacron takes up a suprising amount of space, test it for yourself. I prefer to work with a complete burn, at the expense of some velocity.
As time goes by, I'm leaning more to the opinion that a consistently accurate load needs 100% powder burn.
Verify your load at the range you intend to shoot. A one-hole group at 100 is not related to the group size at longer distance.