Slight update here. After the initial 100@30.9 I took that load to a match this August. (I don’t shoot this rifle a lot) Speeds were close to 2900 and it was just too hot. Blanked (@BulletmanThere's a thread a few pages back with some n-140 info in it. I just did a little break in on a PRS rifle in 6BRA with N140. In Lapua brass already BRA formed in another rifle these were my approx speeds in a new 26 inch barrel and 105 Hybrids:
30.6 - 2820
30.8 - 2845
31.0 - 2855
31.2 - 2875
31.4 - 2910
No pressure signs, easy bolt lift. I'm going to load a hundred at 30.9 and see what the velocity looks like after those are all fired. If I needed to fireform, I'd probably load the 29.6-30.0 range for a lighter load.
I don't think you would go wrong with any of the 6BR brass. Alpha, Peterson or Lapua.