Many years ago, I remember Jim Taylor writing about quiet vermin loads for use around the farm. As I recall, he was using a .357 Magnum levergun, no suppressor, 158-160 grain cast SWC. What made the load so quiet was his choice of powder -- 3031 (I believe the charge was 5.0 grains). I never tried this load in a levergun, but I did try a few in a revolver at our indoor range, and the sound of the bullet impact was louder than the report from the muzzle, even from the short barrel of the revolver (it would be even quieter from a levergun). I don't believe I ever chronographed that load, but I seem to recall Jim saying that they were running 500-600 fps, and thumped barnyard vermin handily.