I have a question on new model Ruger Blackhawk cylinders. Do they interchange with any other Ruger cylinder? A friend has a NM 357 stainless in 357/38, recent production with 38 prefix serial number, 6.5” barrel and protected rear sight. He wants to get a 9mm cylinder. Can he adapt a cylinder or is he limited to just a purpose built 9mm from another NM? Is his frame the same mid frame as a Lipsey flat top 357/38/9? Is his frame/cylinder the same as a early 1970s NM 357/38/9? Thank you.