RL26 seems to be directed towards overbore, higher pressure cartridges and heavy for caliber bullets. Alliant probably published cartridges and loads that they thought would benefit the most from RL26. In some of the published loads, the increase in velocity is small, in other cartridges a fair amount of increase. I see RL26 as almost a "speciality" powder for a relatively small number of cartridges.
I would think Alliant will be offering more load data in the future.
Of course, that doesn't stop loonies from pouring RL26 into everything that shoots.............
