Berns-Martin and, later, Bianchi made upside down break-front shoulder holsters. Bianchi's was the Model 9 (more than one version??). The few I've seen were made for S&W "J" frame and Colt "D" frame revolvers. Bianchi's was harness-detachable and capable of metamorphosing to a strong side break-front for belt carry.

Has any manufacturer or custom maker offered such a spring-operated holster for use with 4-inch Colt "D" frame Detective Special revolvers? Is such a holster currently available?