The biggest problem with increasing the power of the .45 acp in a revolver is not the gun, but the bullets jumping the crimp. Since the case headspaces on the mouth, only a taper crimp can be used. In a semi-auto the bullets are prone to get shoved farther into the case from the nose impacting against the inside of the mag. In the revolver they get pulled out and can tie up the gun if they jump the crimp. With full case head support, you can go higher, but use caution and go slowly. I would recommend Power Pistol powder, as that is the best one to use for loading .45 super ammo. In the acp case this powder is stable and predictable from mild to wild. Follow published load data and you should be OK. But remember your Smith is not a magnum. It is not worth the risk of damaging your gun or yourself for a few extra fps.