When I retired from LE, I did a 4 year stint in Executive Protection. Wearing coat and tie for work, I tended towards shoulder rigs. Older ones I had when a Detective were worn out, so looking around for a better daily rig, I settled on the one pictured below, made by MinuteMan Holsters about 30 years ago. The rig uses interchangeable holsters, held in place by a thick elastic band and a heavy screw. Unsnap the elastic, remove the screw and put in a new holster. Works like a champ. The elastic allows the holster to pivot from vertical carry to horizontal for a fast, smooth draw. Unfortunately, they went out of business 20 years ago, but I still use the rig often.