cast from this Lee hollow-base mold. 405 grains, roundnose, with lube grooves wide and deep enough to hold plenty of lube for black powder. Reviews on this thing are mixed, it's a nose-pour and lots of people have trouble with the base filling out completely, some say the pin that forms the hollow isn't centered.
Having tried it, seems like the big thing is temperature: the lead has to be hotter than I usually pour in order for it to fill completely. Also, I've had no trouble with the bullet dropping out, but:
When you first open the mold, the bullet is sitting on the pin. That means you have to make sure you smoked the cavity well, because if it sticks on either side it'll cause the base to deform. Also, that lead is very soft at that temperature, so you have to be careful about dumping it out for the same reason; best seems to be to turn the mold over so it falls onto a padded surface.
Where I see a real problem in design is the base is stepped: it is full diameter until just before the bottom, then there's a step in so the part surrounding the hollow is a bit smaller. Why, I have no idea; seems like a flat bottom would be both simpler, and would give fewer problems in filling-out.
This time of year, I haven't had a lot of chance to shoot them, a few with a minimum load of A5744, and a few with 68.0 of 2f black. Both shot with no problems and decent accuracy, so there's potential there.
Digging around for reviews, I found a couple where people took the base pin out and modified it so it was no longer forming a hollow, just a flat base. Might not be a bad idea if I can figure out how.