Admiral:
It probably is a combination of the particular lot of powder, and the lot of brass. I've seen this situation with IMR-4350 thru the years. Books have listed 60gr as max w/150gr bullet, but even w/drop tube I've never been able to get that much in a case. 58.0 has always been within 50fps of books though and very accurate. (No experience w/Rl-19 but powders are very similar)
Start with a charge that fills case to base of neck and work up until you find a charge that is slightly compressed. Best load will be one with best accuracy, best velocity w/o loss of accuracy if you have a chrono. My bet will be that depending on your barrel lenght that velocity will be close to "book" even though charge is 2-3gr light. Even as low as 58.0 gr will be sufficient for all '06 use if its as accurate as my rifles are.
In an '06, it is hard to go "over pressure" to a point of danger with the slow burners like H4831, Imr4831, AA3100, or any of the 4350's or Alliant Rl-19,22.
My favorite powders in '06 are H4350,Rl-22 (w/180gr bullets) Rl-15, H414. Best velocities with 150's is with Rl-15 and H414 (over 3,000 to 3,100), but best accuracy is with 60.0 gr of H4350 at 3,000 fps (2 different rifles with 24" bbl's). Though one is soon to get a .338/06 bbl.
With 180gr bullets, 60.0gr of Rl-22 is "It" for accuracy and 2,800fps. (Speer 180 flat base gives 3-shots touching with two different rifles). I really haven't used the 165's much. The 180's are superior in energy and the 150's for velocity/trajectory. To me, the 165's though accurate and versatile just don't "fit".
My older brother has used Rl-19 w/165gr Hornady SST, but prefers the H4350 as well. It is just a little "slow" for the 150's,(as is all "4350's" but accuracy should be outstanding).
As above poster said, 61.0 should be GOOD!
