I wouldn't throw in the towel yet. The longer barrel on my 6BR is more sensitive than that. If had used a 0.3gn ladder I'd have missed one of the nodes. 0.5gn and I might have missed both of them. You might also have a setup with a really bad seat depth.

I start with 3 shot 0.1gn ladder. Depending on bullet I will choose a seat depth that is either jammed or about 0.020 off. When I look at those I pick the range I want and shoot 5 round groups, still 0.1gn. Then I go to seat depth tests.

These days I use a ballistics program, like Quickload or GRT (which is what I use). It can at least let you know how far apart the nodes are. I still run a ladder at 0.1gn difference. Then the obtained vel I can use to adjust the program output.

I also shoot my initial ladder at 100yd to minimize any wind effects.