I have an "as cast" brass frame that is NOT "MR3-DB" marked. It was from the Stan Terhune (Ruger VP) collection. It is only marked with an "A" on the right side at rear bottom, not right side at front bottom as MR3's were. This is $400 postpaid. I sent one to Chad Hiddleson, and he plans to write an article about it later. It was from the company that did not get the bid to make the 1970's brass frames (NO documentation, sorry). Email me at "[email protected]". Thanks, Neil