Originally Posted by Lefty7mmstw
Man, I haven't used h450 for quite a spell. I'd use h4831 data in your wsm since h450 tracks nearly identically with h3831 in the hodgdon #26 manual in both the 270 win and 270 roy. Just make sure you are using mag primers and start a full 10% down from modern data for the cal..
I just did a comparison of a bunch of loading manuals that have data for H-450 in the 270 Win and the 270 Wea Mag. none of which have any data for the 270WSM.
Anyway -- I compared data from 8 of my older manuals (including the Hodgdon #26)-- and you were right that H-450 is very similar to H4831 -- more than any other powder that was in all those manuals. In most of them, H-450 started with the same Min load as H4831 in both cartridges and ended with the same Max load too or within 1 grain of the same Min and Max! The Min and Max velocities for both powders were similar too!
So Ill use the H4831 data and watch for signs of pressure.
Thanks for the answers!