I built a 6ARC gasser to run in PRS last year and played with it some and from my experience the Lever is garbage. Very inconsistent SDs, large ES and temperature fluctuations drastically. That said at 100yds it did shoot decent groups but at long range it's a train wreck as well as being dirty. LR is the very last powder I would consider. In fact, I wouldn't consider any ball powder. LR, BLC2, CFE223, W760 will all meter like water in a cheap powder throw and shoot decent groups at 100yd but if you really want the most from a heavy high BC bullet, look at an extruded powder. They will be a little slower in velocity but you gain so much more in consistency.
What I found that does work well and is Varget, 8208XBR and probably the best is H4895. I didn’t push these hard because Grendel bolts are a known weakness but I got great groups that had great SDs that was temperature stabile, I'd start with any of these.
