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.
Hmmmmm, I have not used 3031 in a .357 before. I wonder if it is any quieter than a fast pistol powder like BE, Red Dot, or Trailboss. Trailboss has always been one of the quietest powders for me and "stupid easy" to use.
19.0 of H322 will deliver a 350 gr in a 45 Colts over the Chrony out of 16" carbine well into the 1200s . QL predicted 18,000 psi for 20 gr . It's dirty and 100 fps more than I wanted when it starts to settle down .......
I was told that 700 was probably optimistic for the revolvers.......and an impressive light show .