I use RL19 in my .300 win mag, and so does my buddy with 168 Gr Barnes X triple shock bullets with 78 Gr of powder. This load shoots good with no pressure problems.
We both shoot Tikka's. I have a Tikka T3 Varmint Synthetic Stainless, and my buddy has a Whitetail Hunter.
I shot 75.5g of R#22 in my 300 Win Mag Sendero with Rem brass, 215's, and 180g Nosler Ballistic tips at 3100 fps with 3/4" groups at 100.
I think that when you are buying one pounds of powder at a time, you are asking for real trouble. When ever you start over with a different lot# of any powder you should assume that there could be as much as a 5% change in burning rate from lot to lot. ONly the inexperienced reloader expects to use the same powder charge from one can to another and get extreme accuracy.
I only rework my load if I at the max pressure wise with whatever powder I am using .
Most of the time I choose a load that is down from max pressure as they are usually more accurate and have a wider spread of powder charges that shoot to the same place with velos very close . That way when I move to a new lot of powder I don't have to worry about a load turning dangerous . Might have to tweak a bit for the utmost in accuracy however .