OCW Accuracy/Scatter Node Question

[WB300]

I've used OCW for Short Action (.308) based cartridges and had great results. Dan Newberry has stated here that accuracy nodes appear in roughly 3% charge weights with scatter nodes being roughly 1.5% away from the accuracy node, however I've only heard this when talking about .308, .260, 7-08, .243, etc... My load testing has good examples of this.

My questions relates to Long Action cartridges:

I'm now starting to prepare OCW loads for .30-06 and .300WM. Should the nodes still appear roughly 1.5% between accuracy and scatter? Or because of the increase in case capacity, do the nodes become more spread?

In dealing with 58-60 grains of H4831 in the .30-06, should the OCW be shot in .4 grain increments instead of .3?

In the .300WM dealing with H1000... same question?

Bill

 

[Dan Newberry]

Bill, as odd as it may sound, this does continue to be the case even to the heavy magnums... the 3% OCW skip pattern is *approximate* but it's generally true. And yes, the 1.5% interspersion of scatter nodes should hold true as well.

When you shoot an OCW test, just cover a large enough range to include at least one OCW and at least one scatter node. That would need to be at least around a 5% increase in powder charge from the lowest to the highest charge. In other words... with a starting charge of 56.0 grains, you'd want to go up to around 58.5 grains or somewhere in there... (being careful of published max data, of course).

Dan

 

[WB300]

Thanks Dan.