Tim - If I were starting with a new rifle and cartridge, I'd load 4 of each charge. Assuming that I do my part that day and shoot well, 4 rounds from each load will tell me what I want to know about how well each load shoots. Working in 1-grain increments, I'll typically leave the range that day with enough data on the targets to narrow it down to 2-loads.

On my next trip, I'll load 10-12 of each of those two final loads and shoot them at 50 again (to confirm what I found on the first trip), and then I'll shoot them at 100. Assuming they're both acceptable at 50, I will choose the better grouping of the two loads at 100. I like to see 6-shots at 50 and 100 to make my decision.

One grain of powder will have little if any impact on the velocity, but you'll be surprised at how much one grain can move the POI.

I used to work up loads for a variety of bullets (cheap bullets, cast bullets, hunting bullets, etc...) Now I find the "premium" bullet that the rifle likes to shoot best, and I stick with it. For prictice or hunting, each of my rifles has one load and one bullet that I know is dialed in, but simplicity is my objective.

Repeat the same drill with solids, and you'll be good to hunt anything, anywhere.