Can you clarify what Reeder meant by "older Rugers"?
The original 3-screw 357s were built on a frame similar in size to the Colt SAA, so yeah, they're a problem. From 1973 forward Ruger built 357s on a 44Mag-size frame and those are what the 356GNR is meant for.
The New Vaquero and 50th Anniversary Blackhawk 357 are scaled back down to Colt SAA size.
My understanding from talking to them is that I *can* get a 356GNR cylinder for my New Vaquero, but I have to run it at "S&W spec" loads versus "Ruger spec". So I could run a 180gr hardcast at 1,350fps instead of 1,700.
Now I can still see some merit and if I can ever find a source for a second 357 cylinder for my gun I'll consider it. I would get slightly more power at the top end but also reduced pressure in medium or low end loads. If I load, say, 158gr LSWC-HP slugs at 1,000fps from my 4.68" barrel in 356GNR cases, it would not surprise me if the pressures were so low fired cases would drop right out of an upturned cylinder. And such a load is really about all you need for personal defense.
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Back to the original poster: virtually ALL of the 357/9mm convertable Rugers floating around are built on the 44Mag-class post-1973 frame. I think it may be "all" but I'm not 100% certain. None of the modern mid-frame 357s like mine have been offered as convertibles and I doubt the pre-'73s were though I'm not certain. I don't think any of the 44Mag-size 357s from 1973 to present are "abnormally weak", I've certainly never heard of it if so. I believe all of those could take "full tilt" 356GNR no sweat.