Glad I found this thread!
I bought a can of US 869 a few years ago and 74 grains behind a 140 MK was under a half inch. Did not have a chronograph at that time.
Defiantly gonna try to find some R33 now.
Maybe some R50?
RL-33 could not best US 869 in the accuracy dep't for me. Tried H50BMG also (Same burn rate as RL-50). My advice is don't bother with it. 869 is my huckleberry. What was very interesting is groups were sub MOA from 70 to 77.o grains with the 139 Scenar and the Scenar doesn't seem to care where it's seated.
