Considering that the main character is LEO, you're relegated to looking for low ride LEO holsters, with/without a swivel. The rig in the show is either an open bottom for a 4" revolver, or a cut off to accommodate Rick's 6" Colt revolver. I've seen various low ride open/closed bottom LEO holsters for 4" K/L and N frames, but never one specifically designed for a 6". The 4"ers should be easy to locate with a bit of research.

Blocker lists various drop models shown with semi-auto pistols. It would be worth a call to see if one specific model could be fashioned for a 4" or 6" revolver. With the popularity of the show, it's a good bet that quite a few folks are looking for similar rigs.

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