I'll put in another plug for RL15. I used to use Varget, but found that RL15 is more consistent from lot to lot. I've had to vary charge weights by as much as (extreme case) 2 grains to maintain a load's velocity.
Now that I use RL15, I'm seeing slight increases in velocity, it meters about like Varget and is very consistent from lot to lot. The label says that it's temperature stable, but some guys still say that it's temp sensitive. It might be, but I live in south Louisiana where the temps can vary from the 50's to the 90's in the same day and I've never noticed a difference that made a difference.
As for the claims of single digit SDs, I really don't know how anyone can make those claims, when all chronys have a margin of error, some of which are in the double digits to start with. All I use a chrony for is to get a good idea of how fast my loads are running and to keep an eye out for big SDs. A load either shoots or it doesn't.
43gr under a 175 SMK get me around 2700 fps and 44gr under a 168 SMK get me about the same.