A guy called Sal on another forum once told me he used 63.5 grains of IMR 4831 and got 2300fps with the 300gr slug and that it was accurate. Some of his other loads seemed reasonably hot, so you might start a bit below that.

Some Winchester data I handwrote into my book says 68.5 gr of Win 785 (still got a bit) should give 2375 fps at 50,500 (psi?)with the 300 gr PowerPoint bullet. Once again, I think that was a maximum. As explained, these sources are bit apocryphal, so take care.

I have not used either of these loads, as the bushfires cleared out our hunting range before some Woodleigh projectiles arrived and I decided to go back to 250 grainers in case of longer shots.

Cheers
- Paul