A 300 grain in a 45/anything makes zero sense to me, but you only need to make yourself happy.
How about for hunting white tailed deer with your favorite lever action?
By going with the relatively light 300 grain bullet I am able to extend the point blank range way beyond that which is possible with a heavier bullet.
I have witnessed the instantly lethal terminal ballistic performance associated a .45-70 300 HP loaded to 2350 fps against white tailed deer. I feel that with the .45-90 loaded to 2650 fps I could shoot a deer in the hoof and it would drop in its tracks (I am exaggerating).
I have never been chased by an elephant while hunting in Maryland/Virginia so I think loading 500 grain bullets would only decrease the performance of my hunting rifle. The point blank range of my scope/rifle would be way shorter (by more than half) and the bullet itself would not be as instantly lethal against deer as a hollow point.
