Birdhunter: ".... because I knew Ruger used cast parts in it, we decided to hold the loads down, somewhat. I now feel the frame is up to about any 45-70 loadings"

Caprivi: "I have seen 20ga in 7x65R, 300, 338win on up to 500/416, the 12ga in 500NE"
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Nothing wrong with casting, especially when done the way Ruger does it. The particular alloy steel formed by the casting is much more important than the casting process itself. Modern high strength alloy steels are way different from earlier days, when most all double frames were made from only mild steel, low carbon steel, usually color case hardened; one can't compare the two.