I am not talking past your question, but rather talking past the middle of your journey to the conclusion you will inevitably reach if you go down the subsonic path but hopefully saving you the cost and time of the learning experience. I can appreciate your intentions, especially in the current climate of component shortages so please realise that
I load 300 blk, 7.62x39.44mag and have also loaded 9mm all to subsonic velocities for hunting.
