I think 'over penetration' is a bit myth and often exaggerated. Know what's behind your target. I also think ball ammo in a rifle cartridge would be a mistake. Simply because it wouldn't be incredibly efficient at stopping compared to a good expanding load. If the bullet doesn't yaw, you've basically made a .30 cal hole. If a JSP doesn't expand for whatever reason, then fine, worst case you've got performance similar to a FMJ, best case, you get .50-70 cal expansion and a nice golf ball or possibly larger exit hole and a very uncomfortable BG.
Ball ammo is for lining up headshots on zombies so you can take 2-3 with one stone. Since we don't live with zombies, I'll take expanding ammo.
BTW, seeing how easy it is to shoot through an interior wall, I'd be nervous to use any cartridge/projectile combination that claims not to penetrate through interior walls. If it can't make it through a bit of dry wall, how do you expect the it to make it though bones, sinew, and flesh adequately to stop the target?
SST is a pretty good projectile, but I'd have to do testing at point blank (SD ranges). Hitting at muzzle velocity may cause unwanted fragmentation of the bullet.
