Not many people shoot cast lead in 30-30. To much is given up. Not like a 45-70 where velocities (and pressures), even on the +P end barely overlap the low end of starting loads for a 30-30 . A bitsy little 308 caliber 170 grain bullet, to work effectively, velocities are generally around 2000 fps and upward to 2400 fps. Too fast for cast lead even gas checked.
So, even if they are intended only as a plinker loads, a plinker cast load in my 45-70 will still hit like a freight train and be a useful hunting load if only at closer distance. One can load and shoot a 45-70 from 900 fps to 1800ish using cast lead 405gr bullets. A 1200 to 1600 fps 170 grain cast load from a 30-30, what can you do with that? But plink. Yeah, I guess you could hunt with a 170gr cast bullet at 1600 fps, but, as I said, you are giving up a lot.
Plus, then, you wind up needing to shoot cast and jacketed in the 30-30 whereas a 45-70 shooter can shoot only cast and still plink, hunt or take on a t-rex if need be. Cannot be said for the 30-30. The 30-30 needs jacketed bullets to be a good hunting round (which it is no doubt).
My current loads for 30-30, 160gr FTX with 34.0gr of Lever revolution powder, CCI LR primer, Winchester nickel brass and the other 170gr Sierra JFP with 34.5gr of Lever Revolution powder, CCI LR primer and Winchester brass. My 45-70 gets cast lead, my 30-30 gets jacketed, both exclusively.
3C