I've rtaken a liing to inverted shoulder rigs for my J Frames. Alessi makes the Guardian, with close molding and a thumb break. It has a six-round dump pouch on the off side that will take a speed strip with five rounds (but not six).
I also use a K.L. Null "SMZ" rig. It is a white polymer harness, with a hook through the trigger guard, snapped to a piece that wraps around the cylinder. Release is accomplished by slightly raising thegun and twisting it to break the snap release. Sounds complicated, but is quick and simple with a litle practice. It is not to be used with anything that has a reduced trigger pull. He makes them for S&W Js and Ks, and about ten years ago he made one for a S&W 24 N Frame for me, but that is not listed on his site now.
Comment - I've had a couple of rigs with speedloader carriers on the off-side, and found that once the harness was finally adjusted for long-term comfort, the speedloaders had to go elsewhere. They always wound up digging into the tender part of the inside of my upper arm. A dump pouch, considered "extra ammo", and speedloaders on the belt or in a pocket, considered "quick loads" turned out better.