I have used COW, cast bullets and jacketed, and all 3 have and do work. If using cast bullets, I tend to use the heavy for caliber bullets with varied pistol powders to get the pressures up and keep velocities on the lower end. I have a few cast bullet manuals and use old Lyman's mostly for a guide to powder charges, vels and pressure.
Properly lubed and heat treated cast bullets, especially gas checked, do not overly lead the bore, as I have used these for decades in varied rifle loads. There were even BR comps using cast bullets, and while I have not shot in these for sometime, I used 30cals with cast 190's with very good accuracy.
I believe all of my 30-30AI brass were formed with cast, same with the Herrett's, and a few others have seen there share. It does work.