Buffalo Bullets have a hollow base. You would have to look at a minnie type bullet mold. Check out the Lee precision website, they have a couple different types. I honestly don't think you'll get the same performance out of a minnie as you do the Buffalo Bullet. Bullets like the Buffalo Bullet and the Hornady Great Plains Bullet are minnie/maxi hybrids. The are designed with a hollow base but are also designed to engrave the rifling when you load for a tighter fit. Minnie bullets are under-bore size and slip right down the barrel.
Huntin Dawg