Thank you for the sensible responses regarding my question on hard cast projectiles. Using hard cast projectiles in rifles is a new thing for me. My original intention was for plinking as the Marlin has Ballard rifling.

Achieving that sort of accuracy out of my leveraction rifle with lead cast projectiles prompted me to do something different and challenging one Saturday afternoon, go head shoot some rabbits. Five rabbits for five shots. Seeing the length of ploughed up soil made me think these 405gn slugs could possibly be good on a pig. Hence why I asked the question.

I agree with Drilling Man, the only way to know is to conduct a wet newsprint penetration test with these lead projectiles. Just have to accumulate more test media.

For the record, to date I have only ever used 300gn JHPs doing 2140ft/s on deer and pigs. They are the original "one hit wonder".

Now I'm curious to know what the old blackpowder Bear/Buffalo load was for the 45-70 during the 1870s-1880s.