bigcountry

Probably the closest load you could come up with to match150gr of smokeless is IMR4198 with a load of 49gr with 300gr jacketed bullet.

But you can acheive the same thing with 60gr of IMR4895, or 38gr of 2400 or 54gr of RL7.

All these powders would show simular muzzle velocities with a 300gr bullet but pressure curve would look totaly different to acheive the same thing.