As far as I know, all the medium frame flattops have steel grip frames whether stainless or blued. All of mine are. Also the grip frame is the smaller (more like Colt) plow handle (XR-3)... Ie. same as the New Vaquero grip frames (if plow handle style) .
Yes, all the new model Flat Tops in both large frame and mid frame sizes (and all New Vaqueros) have steel grip frames. They are the smaller XR3 size and they are the only Ruger grip frames that are only 7/16" thick. All other grip frames are 1/2" thick.
I have an 86-prefix New Model Super Blackhawk .44Mag., and a 48-prefix New Model Blackhawk 45LC., both of which I put Hogue Monogrips on as they fit me better than the 'plowhandle' Ruger grips.
I just picked up 521-prefix (2014) New Model Blackhawk 45LC/ACP convertible, and found that the Hogue grip doesn't fit.
As stated by Hondo44 above, it has the XR3 7/16" steel grip frame which is contoured slightly differently, and the grip locator roll-pin is positioned differently than the XR3-Red frames.
Am I correct in assuming (hoping) that a Pachmayr RB03137 Presentation grip will work on it, or can be modified to work ??
Thanks in advance, DaveF.