Maybe something else to think about but I have a couple of guide guns and shoot a lot of subsonic ammo. My favorite load uses 15.2 grains Unique powder with Remington 405 grain JSPs and averages 1100 fps. For general plinking I use cast 405 grain bullets and Trail Boss powder and load them to similar velocities. Either load is easy on the shoulder and accurate too.
Nice looking JMs. Kept them MINT !
Don't ask me about my military service or heroic acts...most of it is untrue.