Food for thought...slower powders meant more for overbore mags have proven to be accurate in my "overbore" .22-250 and heavier bullets. The 64 grain .224 isn't really "heavy" but is heavier than standard 55 grainers.
There isn't load data out there (that I know of, but maybe "Pet Loads" may have some???) for things like Retumbo. I think Hodgdon has 1 load for H1000 and the .22-250, so a guy would have to real careful. I won't post my data for obvious reasons, but I was pleasantly surprised by some of the velocities and accuracy I got with both the 63 Sierra and the 77 Sierra. Some of it was terrible accuracy wise, but other loads were great.
