Some of the best 600 and 1000 yard scores I've had were with new brass. Add neck lube, Run em through a FL die and your GTG. I've always had to tweak loads slightly from new to once fired brass.
People will say it doesn't apply because we're hunting....4 out of the top 3 spots back in Oct. at the Long Range Fclass Nationals (1000yrds) was shooting new brass.