Howdy Doc O,
Are you sure that's a Richards-Mason and not a '72 Opentop? The reason I ask is that the R-M's have previously not been offered in 45LC, while the OT's have offered 45LC starting about a year ago. Also, the 1860 R-M's previously were only offered with Army grips, with steel gripframes (and the 1851 R-M's were only offered with the brass gripframe and Navy grips). Opentops have been available with either Army grips (7 1/2" barrel only) or Navy grips (any barrel length). If it is indeed an 1860 R-M in 45LC with a Navy grip, then that is two new options for the gun.