Soundguy, I size my boolits to 0.316” and cast them from about 96/2/2 Pb/Sn/Sb aged from a week to 6 months. I drive them hard enough to get 0.001” case head expansion. The nose of my Accurate 31-117E is a bore ride with some clearance at 0.300”. The ones I've recovered all show the bore ride portion obturated to fill the grooves. That might be the mechanism that lets me shoot that soft alloy at way over 357 Magnum pressures without stripping the riflings. The whole length of the boolit grabs the rifling. It also seals really well.
If you get the urge to revisit shooting cast, I suggest you try soft boolits with pressure up near 50,000 psi and see if they strip and tumble or obturate and shoot straight and clean. My 2cents.