My favorite load is 6 grains of IMR 800x with CCI primers. 255 gr SWC or 250 gr RNFP. I have taken these plenty hotter but pass thrus will be almost garaunteed even at moderate velocities. Pins wont stand a chance.
My Kimber pistol has been modified by applying a 20lb Wolf spring, flat bottom firing pin retainer, and 28 lb mainspring. I use metal form mags as they have provided with a lifetime of reliability.
The 6 grain loads cycle flawlessly and are on the lower end of the velocity spectrum for the boolits.