I'm trying to repair an old S&W Registered 357 made in 1938.- Does anyone know what is the angle of the forcing cone? It is badly eroded, perhaps by many thousands of full power round.-
I have heard of 11 degrees.- Any help highly appreciated

The first question to ask is if the piece has lost accuracy or is spitting lead? A check of barrel/cylinder alignment (range) and yoke alignment is also suggested as these may reduce any issues so that the forcing cone isn't an factor. I once had an abused single action with rough cone, had no effect on grouping.

A machinist could establish the original angle with a dial indicator. I believe that was an 18 degree angle, but cannot swear to it. More modern revolvers use an 11 degree angle forcing cone. Brownells has both hand tools and gauges for forcing cone work. I tend to cheat and use a lathe.

Depending upon original machining, it may be possible to recut the orignal angle to 11 degrees with no other changes. If it's too bad, it'll be necessary to set the barrel back one thread and re-cut the forcing cone. This ususally requires trimming the ejector rod and center pin to match.

I have recut all my .357 forcing cones with a 5 degree forcing cone. In the past, I used an 11 degree for .45s, but have switched to a 5 degree for them, too. 7 or 8 would possibly be best, but I don't know where to get a tool to do it.

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Tom

Thank you guys so much, your advises are very enlighteing as I see the proper angle is not determinant.- After my first posting I did some tests with my Ramson rest and got a five shot group with a ligt target load, of .55" at 50 feet.- This is not something definitive but makes me to review the idea of a full overhauling.- If I can get a full power load of similar prformance it's better not to try to fix what it is not broken.- Thank you guys again