It really depends on what you want to use the gun for. Since they both use the same .44 ammo, it is relatively easy to keep them loaded. In a purely damage prospective, Lincolns repeater deals 5 less damage per shot than Blackhawk and has a longer delay between shots. However, Lincolns repeater is 100% accurate, meaning that outside of V.A.T.S. the shot goes exactly where you are aiming. On the other hand, Blackhawk, though having a scope has a slight spread for each shot, making those long range snipes much more difficult. In the end, if you are successfully hidden, the more accurate Lincolns repeater will down almost anything with one headshot, witch is great for stealth characters. The increased damage and fire rate of Blackhawk is great for those run and gun situations.