Moon clips.
Your cylinder must be cut for them. I have them in 7-shot .38 (S&W 686+), 8-shot .38 (S&W 627), and 6-shot .45 (S&W 325). They hide pretty well in a
DeSantis "Second Six" holster (originally designed as a speedloader pouch) that is a pretty nifty product. It actually splits the rounds over either side of your belt--half inside, half outside. A big help with concealment.
For a J-frame I use speed strips. I haven't gotten around to having any of my J-frames cut for moon clips yet.