A .32 will suffice for SD CC. Placement is everything no matter what caliber you carry. The .32 has very little recoil in a metal gun so second shots are easier to keep on target. A 6 oz. semi auto .32acp might have more recoil than expected but it could conceal easier than a revolver also.

I would say most anyone being shot at with even a .32 would still have the instinct to run and flee.