I think metacarpal problems slowed Lynn down on his casting. That and a move into town, but he may be doing some machine casting now.
I usually don't run my M625-6 too much over 1100 fps with 255 gr bullets. 270 gr bullets are only in the 950 fps range. However, Clark's Custom guns uses 625s for their .460 Rowland conversion, so I guess that's a permissible velocity.