I have a R101 in 38Spl. 3" brl.
When researching it on the web, I found that it has the same strength cylinder as the 357, so I load very hot 38Spl loads in it.
At $250 (used) it is one of the best buys I ever did. Like other Rugers, it is built like a tank and much heavier than a Smith.
A 4.2 R101 in 357 would be a nice strong gun.