Yep. Difference based solely on standard rifling pitch associated with the cartridge name. I was trying to think of other examples of that being done, but nothing is popping into the feeble little gray cells.
With the 85 grain Bullet, pushed all the way to maximum pressure, QuickLOAD is suggesting that RL 17 is nearly king of the velocity heap (except for a couple of European powders we don't get here), getting that little bullet to over 3500 fps in a tight 24" test barrel. If you're willing to lose 110 fps, good old IMR 4895 is right up there at 3390 fps. It is outperforming IMR 4350 by about 60 fps in the simulation, and outperforming RL 19 by 150 fps, though Accurate 4350, which is faster than the IMR product, is 20 fps faster than IMR 4895.
The reason powders that are faster burning than you were considering are doing so well in the simulation is the light bullet is pushed forward so easily and quickly that it expands the space the powder is burning in faster than the slower powders can make enough gas to fully keep up with it. On the plus side, it means smaller charge weights producing more economical shooting.
