After hearing about Audette's ladder load development and seeing Joe B's attempt at shooting it at 100yds instead of Audette's 300yd test, I decided to give it a try for myself at 100yds. Anyone wanting to know how it works can go to this address on the web to read an excellent article by Randolph Constantine:
Having shot 3 different powders in championship loads in NT2004, NT2005 and NT2006, I knew what load worked with the 3 powders, so now it'll be easier to look into the ladder load results. The rifle is my Savage M12VBSS in 308Win. and the CB is a Egan MX4-30ARD, 214gr., 1.296” long. In the attachment below, the bull target on the left is the load I used in NT06 with Vihtavouri N135 powder at 30.5gr behind the MX4-30ard, shot this day. The wind was gusty the day I shot, so I held conditions for the 4 shots in the cluster and 1 shot out to see just how far the wind gust would take it right. Aim point was the dot.
The middle grid target was the actual 14-shot group with 1ea. loads in .25gr increments from 28gr to 31.25gr. The grid target on the right shows the impacts in sequence.
The Bar-line graph below lists the sequence number, vertical impact position from the lowest shot to the highest shot in the range, the powder charge and the velocity. Looking directly at shot #11,12,& 13, they are the tightest clump in the graph, right where my best load is that I call the 'primary load'. There is also another larger group together at shots #1,2, & 3 which is probably a 'secondary load' which probably isn't as efficient as the higher pressure load at #11,12,& 13. Even though the group looks fair in size, it doesn't show just how dispersed the shots are from #3 - 10. In this instance, the shots went higher in elevation with the powder charge increase................Dan