Okie John and Lost River are right. I've not done cast with .30/30 but used to play with light jacketed bullets in my crusty old Trapper when my kids were still kids.
Get a Lee Loader for .30/30 and scour reloading stores for Speer 100-grain Plinkers. They're a very mild plinking load at 1,500 and can provide good visuals on vermin at 2,000+.
I found a new Marlin 336 after Dad died he'd that squirreled away in a closet and never fired. It's been sitting in my safe for near 4 years. May soon drop a small scope on it for a .22 Magnum substitute up at The Ranch.