Could be lot to lot variation seen that before in RL 15. Have not bought any new RL 15 for aprox. 5 years. The Whelen does well with most mid range powders.
My 22" 35 Whelen with 250 Gr Speer shot the best around 2500 FPS with RL 15.
My Std load for my Rem 7600 35 Whelen Pump rifle is 56 Gr of IMR 4320 with usually the Speer 250 Gr bullet. about 2525 FPS, Or around 56 gr older RL 15 with same bullet.
