I have run this powder in the .308, .338-06, 35 Whelen AI, and 9.3x62, and all of that experience has suggested its combination of bulkiness and burn rate might be near perfect for lighter weight bullets in the 30-06. In all of the above, it was a struggle to get enough powder in the case to get the best of it.
Today I finally got to the range with some 155 Scenars loaded over RL15.5 in my JC Higgins M50 30-06 (CCI 200, .010" off the lands, R-P brass). This rifle tends to develop max velocities at a grain or two below the published "max", and thus, that's where I tend to stop. And I will certainly "stop" right here (at 54 grains). This needs to be shot a couple more times to validate it's not just a fluke but it bears all the earmarks of a perfect combination - groups tighten as one approaches max and velocity variations diminish. Of course, SD is essentially meaningless for 3-shot groups, but these results scream for much more work.
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I'm going to also post this to the other RL 15.5 discussion threads we have going here. I am thinking 30-06 165 grain bullets might also do nice with 15.5.

Cheers,
Rex