Big Bore Lead vs Jacketed bullets

[MtnMike2]

I own a Winchester Model 1886 in 45-70. I reload and want to put together some cartridges for black bear. There are some hot rounds on the market that use pure lead bullets - Garrett, Buffalo Bore, even Cor-Bon seems to be a lead bullet. Is there any advantage to using a pure lead / alloy bullet as opposed to a jacketed bullet ?