Based upon Speers recently released data, I trialed Power Pro 2000MR under 250 gr Partitions. Accuracy is superb, so it is going on a moose hunt in a few weeks.
Alliant and Nosler dropped max load recommendation on RL15 rather abruptly. I experienced pressure spikes, so discontinued use as there is no shortage of alternative choices.
Strongly suggest that anyone considering RL15 and 250 gr bullets in their Whelen, look at the published data, and work up carefully.
A 250 gr moving much above 2500fps is geting into dicey territory.