My " everyday load " for my 357's is 7.5 grs of WSF using a 158 gr cast bullet . I shot a lot of those in my S&W 681 , and I get no leading of the barrel . I have shot many 180 gr cast bullets on top of a max charge of W296 (current load data ) and again , no leading of the barrel .
If you are getting a leaded barrel , you have issues with that revolver , IE: undersize cylinder throats , tight spot where the barrel threads onto the frame etc . Don't blame the cast bullet nor think that cast bullets can't be driven 1300+fps with no sign of a leaded barrel . When a revolver has proper internal dimensions , you are using a good bullet lube , a proper cast bullet and your bullets are a " proper fit " in size , the leading problem goes away . Gas checks are not necessary . I speak from many yrs of experience .