The range that I shoot at has target berms at various distances, but I've noticed having some difficulty finding the 'nodes' at longer distances as well as up close... at closer distances, as mentioned, everything seems to clump right together. At longer distances, say 300yds, on this range, there is enough problems from the wind (sits right on the edge of a gulley, and gets a pretty strong 'shank' effect on the shots... very difficult to see because the wind patently doesn't exist except for maybe the last 50 yards or less) and the mirage (big dirt Highpower berm w/ target carriers, get a lot of nice mirage off of it distorting the target face, makes accurate aiming a bear).
I've actually had very good luck doing the OCW method as outlined by Dan Newberry aka green788 on other forums. A simple google search will probably get you all the information you need on it. It's basically an extension of the ladder test methods, designed to address a few things that the author didn't like about the original Audette method. Both work, as far as I can tell.
One thing that I found interesting is that while as I mentioned, I've had problems finding the right times of day when the wind and mirage cooperate to make precise shooting feasible @300yds, it's considerably less of a problem @ 100yds on this range. What I've done w/ some success is shoot the 3-shot groups for the OCW ladder @ 100 yds... and since I use RSI Shooting Lab ballistics software and it has an additional target analysis module... using this it's pretty easy to isolate the vertical dispersion that identifies the node(s), even at only 100yds.
YMMV,
Monte
