Originally Posted by Lefty7mmstw
rl33 is a few % slower than retumbo, so you can take retumbo data, start at mid-load, and work to a few grains over the top. Talk to azshooter on this as he has worked more with rl33 than I have.
One instance I have used rl33 in is the 300rum with 225 grain hornady hpbt bullets. I was able to go to 95 grains rl33 at normal pressure getting 3000 fps using rp brass and a 215. Hodgdon is getting retumbo to 89 grains at 2900 fps with the 220 partition.
Thanks, Lefty7mmstw, good to know, unfortunately at this time there isn't any RL33 available here.
Even though ADI powders are plentiful, they still don't produce the kind of accuracy or velocity I have got with Alliant powders, double base powders are more predictable, H1000 is a good example of only working in a narrow pressure window, I'm still yet to try Retumbo in anything, but suspect it will be the same.