I'm currently working on the same load as you for my 12LRP. Also using RL17, CCI200, and Nosler CC 140s in fresh Hornady brass.
In my rifle, COAL when seated to the lands is 2.775 with the Nosler 140 CC.
40.8 - 41gr of RL17 is where I started to see the best groups on the low end. I...