Originally Posted by 7stw
Hey lefty, I just read in Rifleshooter mag that a max charge of RL 33 , 85.7 grains behind a 175 speer will yield 3033 fps, versus 74.0 rl25 @ 2947, all in a 24 inch barrel. This stuff looks interesting in the STW with heavy bullets. I think it will really benefit the larger calibers with heavy bullets even better. My guess is the burn rate is similar to VN-170. Don't know about the temp sensitivity though!!!!!
I'll buy some and work it over when it shows up, and I don't wait for data. I've been working with mil-surp long enough to work with unknown powders. I'll tell ya though, even after doing my own developement for years, I still get apprehensive about that first trigger pull with an unknown powder. After I know where I've landed, it's cool, but that first shot......... I've already worked rl50 over in the 300u, and it's good but it needs rather heavy compression to get 3K out of a 225, I bet I could break 3100 with the 300u with 33 if it's slow enough. The stw hasn't eaten rl50 as it isn't quite as over-bore as the 300u.
An 80 fps edge with rl33 is pretty good, as rl25 is one of the best in the stw.
The new nitrochemme(?spelling) powders have a different powder structure as far as burn rate modifiers as far as I've read, and it's supposed to help with temp sensitivity. I have seen at least some speed difference even with the hodgdon(wicked temp extremes here in the Dakotas), but it seems as though when a lot of this stuff is temp sabilized, they take some speed off the table. H4831 is a prime example. With new powder, I can barely get 3050 to 3100 fps with a 180 in my 300win; in old paper can stuff(war surp), I could get 3150 and it wanted more.