I bottom pour EVERYTHING from a Lee 4-20 with excellent results. That is until I start pouring my 65cal round balls and 1" round weights.
I use a Rowell ladle for those with good results. The Lee just cannot pour the Pb fast enough for large cavities like that.
But I have never found a standard boolit mold in Al, Fe, or brass (up to 45 cal 350gn the largest I cast) that would NOT work with my bottom pour pots.
Preheating all your molds on an electric hot plate to FULL casting temperature sure helps with larger molds and cavities. Try it!