should have my custom rifle finished here in the next couple months and am going to start with R33 and the 140's. but need a good starting charge. not finding any info online and I contacted berger but they havnt had a chance to test it yet.
So far, my experience with RL-33 has shown it to behave as a considerably slower powder than Retumbo in .264 Win Mag. I started my workup at 66.0 grains and went up in one grain increments from there, solely to establish pressure limits.
Once I found max, I backed off 10% and performed an OCW workup. The 66.0 grain load clocked in the 2600's from a 26" barrel. There was a lot of headroom from there to max.
ETA: I did the pressure limit workup with Berger 140 VLD's. If you are using more blunt bullets, such as Partitions, you may wish to use the starting charge for Retumbo (as listed by Hodgdon) and work up.
In my load work with the .264 Win Mag, I have found Quickload data to track closely with actual data, using RL-33. That has not been the case with Retumbo.
When I did my initial load work to confirm Quickload predictions in my rifle, I found Quickload predicted powder charges approximately 3.7 grains higher than actual for a given muzzle velocity. For example, QL predicted 73.67 grains of Retumbo would produce 3153 fps. During initial testing, 70.0 grains of Retumbo produced 3156 fps.
In the short time I have used Quickload, I have found it to be a valuable tool. It can also lead one dangerously astray, if it is not used with caution.
Agree with that, when my barrel was new it would top out with a few grains less than predicted. As I get more miles on the barrel the better it tracks.
Just got my hands on some R26. Without even QL to help it will take time to work up to find the upper end.
I just completed my load workup with RL-33 in my .264 Win Mag. 78.5 grains produced ejector marks. That was my first pressure sign. RL-33 did not shoot well in my rifle. I had excellent results with Retumbo, so that will be my go to powder in the .264 Win Mag.