I'm in the process of working up a load, but also have unfired brass.
So I'm wondering if varying the powder charge will still help narrow down charges to look at closer later with fired brass, or if its a waste of time until the brass is fire formed.
I expect brass will have some affect, but no idea if its a significantly greater affect than incrementing powder 0.3gn
Anyone have an idea? Perhaps results from a known load with new brass?
My brass source is actually 120 rounds of ADI Outback ammo, which has a nice temperature independent powder. Seems a shame to waste it on fireforming brass, and it gave me an excuse to fiddle. So I've made up an aluminium collet which works great with a pair of vicegrips, and disassembled 50 rounds. I'll save the proj & powder for later, once the brass is formed and I've an idea of optimum load. There was a fair variation in factory charge too, avg 46.3 gn, with max variation 45.9 to 47.0, all lightly compressed. I was surprised to see a full grain of variation.