In 1958, Remington and Winchester were only offering 2 bullet weights in 250-3000 factory ammo, 87 and 100 grains. They were offering 3 bullet weights in 257 Roberts factory ammo, 87, 100, and 117 grains. While the 87 grain load in the 250-3000 might be aimed at the 1-14" ROT rifles, the same bullet in the 257 Roberts would seem to be out of place given the lack of ROT restrictions and the other available bullet weights.