First, you should check your local laws and read all regulations regarding muzzleloader hunting.

Look into a good 50 caliber inline; I highly recommend a Thompson/Center Encore or Pro Hunter. It's a pretty versatile muzzleloader. You'll have plenty of options as far as scopes vs. open sights, pellets vs. loose powder, and full bore projectiles vs. saboted projectiles. Barnes makes great lead-free bullets.

In case you're wondering about their killing power or accuracy, my sister used my dad's T/C to shoot a buck at 221 yards last season.