Deja Vu! I understood exactly what you wanted.

When I lived in Pensacola, Florida I belonged to a range like this. A public road ran by the benches and I was warned to carry or take the gun with me when I changed targets.

When ever I bought a S&W or Colt I always purchased an appropriate holster for it. I was always big on Bianchi and many of the holsters I owned could be used with more then 1 gun.

Keep in mind your 624 is not a 6" but a 6.5". I used an X15 shoulder holster for mine and it also worked with a 6" 29 and 6" 28. Bianchi is no more I believe but as suggested try a chest holster. Good luck, and thanks for the memory.