I’m not too sure if you have subsonic 20 bore cartridges in the US. Gamebore load them here in the UK and I use them a great deal on the shooting ground to teach young ladies and small lads. They are called ‘low noise’ and the recoil is unbelievably low. They are 28g (1oz) but you would think they were half that. They have considerably less recoil than a 21g (3/4 oz) at standard velocity. I have to say I have never tried them on live quarry but they will break clays very satisfactorily out to a good range. I am not too sure of the velocity – but it feels slow – but they seem to produce very even patterns by the consistency of the breaks. I think you can get Gamebore cartridges in the US and they would be worth a try. A light 20 bore can be a brute with recoil unless you get just the right cartridges combination.