Before you go off the deep end and buy thousands, why not buy as small a quantity as they'll sell you and at least try them first? Bullet diameter matters a helluva lot, and pistol bullets don't need to be crazy hard. If you haven't measured your throat diameters, and considered the velocity you'll be shooting them at, you're simply rolling the dice. This stuff ain't rocket science, but there are protocols to adhere to if accuracy without leading is desired.
BHN 12? That's a lot harder than 90% of what I shoot, and a bit harder than than the other 10%. Check out how hard the bullets are in factory ammo.....
Amen! Shoot a hard cast .451diameter acp bullet down a Smith with .454-456 throats and get your Lewis Lead Remover ready.
For pistol plinking, swaged lead bullets from Hornady or Speer work great at moderate velocities and are accurate.
