If push comes to shove you could use the .50 on em', just load way down in the powder dept., say 30-35grs and have at it. That should give enough power to thump em' without being full power.
On the subject of .32's, the only one that I ever owned was a Dixie Gun Works Tennessee Poor Boy and it'd drive tacks with a .312 round ball and 15grs. of 3fg. as long as I ran a spit patch down the bore between shots. If I didn't it'd foul and loading would be pretty hard. Anyway, good luck huntin'.